Add support for new pnacl native toolchain driver

ports/zlib/nacl.patch

Index: ports/zlib/nacl.patch
diff --git a/ports/zlib/nacl.patch b/ports/zlib/nacl.patch
index 720f3b8766959025c34d20ac45225c799038ade1..a7a5c3c1bcec85ef4ce9d101e0b507d735eae8b9 100644
--- a/ports/zlib/nacl.patch
+++ b/ports/zlib/nacl.patch
@@ -1,7 +1,20 @@
 diff --git a/configure b/configure
 --- a/configure
 +++ b/configure
-@@ -188,6 +188,13 @@ if test "$gcc" -eq 1 && ($cc -c $test.c) >> configure.log 2>&1; then
+@@ -20,7 +20,11 @@ date >> configure.log
+ 
+ # set command prefix for cross-compilation
+ if [ -n "${CHOST}" ]; then
+-    uname="`echo "${CHOST}" | sed -e 's/^[^-]*-\([^-]*\)$/\1/' -e 's/^[^-]*-[^-]*-\([^-]*\)$/\1/' -e 's/^[^-]*-[^-]*-\([^-]*\)-.*$/\1/'`"
++    if [ "${CHOST}" = "le32-nacl" ]; then
++      uname="pnacl"
++    else
++      uname="`echo "${CHOST}" | sed -e 's/^[^-]*-\([^-]*\)$/\1/' -e 's/^[^-]*-[^-]*-\([^-]*\)$/\1/' -e 's/^[^-]*-[^-]*-\([^-]*\)-.*$/\1/'`"
++    fi
+     CROSS_PREFIX="${CHOST}-"
+ fi
+ 
+@@ -188,6 +192,13 @@ if test "$gcc" -eq 1 && ($cc -c $test.c) >> configure.log 2>&1; then
    *BSD | *bsd* | DragonFly)
          LDSHARED=${LDSHARED-"$cc -shared -Wl,-soname,libz.so.1,--version-script,zlib.map"}
          LDCONFIG="ldconfig -m" ;;