[gcc] Add nacl to libstdc++'s list of glibc-based architectures

gcc/libstdc++-v3/crossconfig.m4

 dnl
 dnl This file contains details for non-native builds.
 dnl
 
 AC_DEFUN([GLIBCXX_CROSSCONFIG],[
 # Base decisions on target environment.
 case "${host}" in
   arm*-*-symbianelf*)
     # This is a freestanding configuration; there is nothing to do here.
     ;;
@@ skipping 113 matching lines @@
     case "$target" in
       *-hpux10*)
         AC_DEFINE(HAVE_ISINF)
         AC_DEFINE(HAVE_ISINFF)
         AC_DEFINE(HAVE_ISNANF)
         AC_DEFINE(HAVE_FINITE)
         AC_DEFINE(HAVE_FINITEF)
         ;;
     esac
     ;;
-  *-linux* | *-uclinux* | *-gnu* | *-kfreebsd*-gnu | *-knetbsd*-gnu)
+  # TODO(mseaborn): Maybe we should handle NaCl by changing NaCl's
+  # configuration name to "nacl-gnu", so that we do not need an extra
+  # case here.
+  *-linux* | *-uclinux* | *-gnu* | *-kfreebsd*-gnu | *-knetbsd*-gnu | nacl*)
     GLIBCXX_CHECK_COMPILER_FEATURES
     GLIBCXX_CHECK_LINKER_FEATURES
     GLIBCXX_CHECK_MATH_SUPPORT
     GLIBCXX_CHECK_STDLIB_SUPPORT
     AC_DEFINE(_GLIBCXX_USE_RANDOM_TR1)
     GCC_CHECK_TLS
     AM_ICONV
     ;;
   *-mingw32*)
     GLIBCXX_CHECK_LINKER_FEATURES
@@ skipping 108 matching lines @@
     AC_DEFINE(HAVE_SINHF)
     AC_DEFINE(HAVE_SQRTF)
     AC_DEFINE(HAVE_TANF)
     AC_DEFINE(HAVE_TANHF)
     ;;
   *)
     AC_MSG_ERROR([No support for this host/target combination.])
    ;;
 esac
 ])