Extend UTF-8 support to the 32-bit mingw host.

Prevent any name mangling in HOST_EXTRA_OBJS_SYMBOL
such that the linker always finds it by that name.

Also add the .manifest file as an explicit
dependency in the make rule such that the
object gets re-built if it changes.

gcc/ChangeLog:

	* config.host: Pull in i386/x-mingw32-utf8 Makefile
	fragment and reference utf8rc-mingw32.o explicitly
	for mingw hosts.
	* config/i386/sym-mingw32.cc: prevent name mangling of
	stub symbol.
	* config/i386/x-mingw32-utf8: Make utf8rc-mingw32.o
	depend on manifest file explicitly.

Signed-off-by: Jonathan Yong <10walls@gmail.com>

gcc/config.host

@@ -232,10 +232,11 @@ case ${host} in
     ;;
   i[34567]86-*-mingw32*)
     host_xm_file=i386/xm-mingw32.h
-    host_xmake_file="${host_xmake_file} i386/x-mingw32"
+    host_xmake_file="${host_xmake_file} i386/x-mingw32 i386/x-mingw32-utf8"
     host_exeext=.exe
     out_host_hook_obj=host-mingw32.o
-    host_extra_gcc_objs="${host_extra_gcc_objs} driver-mingw32.o"
+    host_extra_objs="${host_extra_objs} utf8-mingw32.o"
+    host_extra_gcc_objs="${host_extra_gcc_objs} driver-mingw32.o utf8rc-mingw32.o"
     host_lto_plugin_soname=liblto_plugin.dll
     ;;
   x86_64-*-mingw*)

gcc/config/i386/sym-mingw32.cc

-char HOST_EXTRA_OBJS_SYMBOL;
+/* Prevent any name mangling to make sure that the linker
+   will always find the symbol. */
+char HOST_EXTRA_OBJS_SYMBOL asm ("HOST_EXTRA_OBJS_SYMBOL");

gcc/config/i386/x-mingw32-utf8

@@ -27,7 +27,8 @@
 # The resulting .o file gets added to host_extra_gcc_objs in
 # config.host for x86_64-*-mingw* host and gets linked into
 # the driver as a .o file, so it's lack of symbols is OK.
-utf8rc-mingw32.o : $(srcdir)/config/i386/utf8-mingw32.rc
+utf8rc-mingw32.o : $(srcdir)/config/i386/utf8-mingw32.rc \
+  $(srcdir)/config/i386/winnt-utf8.manifest
 	$(WINDRES) $< $@
 
 # Create an object file that just exports the global symbol