build: detect the right `ar` tool

configure

Index: configure
diff --git a/configure b/configure
index 2bf5fe0a0d4214e1f622e51e6490bb55fbbb4651..b1519c394c59c0abcb01d2789323fdea3e9d790c 100755
--- a/configure
+++ b/configure
@@ -674,6 +674,8 @@ CPPFLAGS
 LDFLAGS
 CFLAGS
 CC
+ac_ct_AR
+AR
 MAINT
 MAINTAINER_MODE_FALSE
 MAINTAINER_MODE_TRUE
@@ -4041,6 +4043,178 @@ else
 fi
 
 
+
+if test -n "$ac_tool_prefix"; then
+  for ac_prog in ar lib "link -lib"
+  do
+    # Extract the first word of "$ac_tool_prefix$ac_prog", so it can be a program name with args.
+set dummy $ac_tool_prefix$ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_AR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$AR"; then
+  ac_cv_prog_AR="$AR" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_prog_AR="$ac_tool_prefix$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+AR=$ac_cv_prog_AR
+if test -n "$AR"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $AR" >&5
+$as_echo "$AR" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+    test -n "$AR" && break
+  done
+fi
+if test -z "$AR"; then
+  ac_ct_AR=$AR
+  for ac_prog in ar lib "link -lib"
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_ac_ct_AR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$ac_ct_AR"; then
+  ac_cv_prog_ac_ct_AR="$ac_ct_AR" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_prog_ac_ct_AR="$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+ac_ct_AR=$ac_cv_prog_ac_ct_AR
+if test -n "$ac_ct_AR"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_AR" >&5
+$as_echo "$ac_ct_AR" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+  test -n "$ac_ct_AR" && break
+done
+
+  if test "x$ac_ct_AR" = x; then
+    AR="false"
+  else
+    case $cross_compiling:$ac_tool_warned in
+yes:)
+{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
+$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
+ac_tool_warned=yes ;;
+esac
+    AR=$ac_ct_AR
+  fi
+fi
+
+: ${AR=ar}
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking the archiver ($AR) interface" >&5
+$as_echo_n "checking the archiver ($AR) interface... " >&6; }
+if ${am_cv_ar_interface+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+   am_cv_ar_interface=ar
+   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int some_variable = 0;
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  am_ar_try='$AR cru libconftest.a conftest.$ac_objext >&5'
+      { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$am_ar_try\""; } >&5
+  (eval $am_ar_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      if test "$ac_status" -eq 0; then
+        am_cv_ar_interface=ar
+      else
+        am_ar_try='$AR -NOLOGO -OUT:conftest.lib conftest.$ac_objext >&5'
+        { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$am_ar_try\""; } >&5
+  (eval $am_ar_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+        if test "$ac_status" -eq 0; then
+          am_cv_ar_interface=lib
+        else
+          am_cv_ar_interface=unknown
+        fi
+      fi
+      rm -f conftest.lib libconftest.a
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+   ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $am_cv_ar_interface" >&5
+$as_echo "$am_cv_ar_interface" >&6; }
+
+case $am_cv_ar_interface in
+ar)
+  ;;
+lib)
+  # Microsoft lib, so override with the ar-lib wrapper script.
+  # FIXME: It is wrong to rewrite AR.
+  # But if we don't then we get into trouble of one sort or another.
+  # A longer-term fix would be to have automake use am__AR in this case,
+  # and then we could set am__AR="$am_aux_dir/ar-lib \$(AR)" or something
+  # similar.
+  AR="$am_aux_dir/ar-lib $AR"
+  ;;
+unknown)
+  as_fn_error $? "could not determine $AR interface" "$LINENO" 5
+  ;;
+esac
+
 # By default we simply use the C compiler to build assembly code.
 
 test "${CCAS+set}" = set || CCAS=$CC
@@ -5545,7 +5719,6 @@ fi
 
 
 
-
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for grep that handles long lines and -e" >&5
 $as_echo_n "checking for grep that handles long lines and -e... " >&6; }
 if ${ac_cv_path_GREP+:} false; then :