Add a UTF-8 resource when building for Windows

Add a UTF-8 resource when building for Windows

If a resource compiler is available, use it to add a UTF-8 resource
to the GNU Make executable on Windows.  As a result, GNU Make will
use UTF-8 as its ANSI code page, enabling it to work with UTF-8
encoded Makefiles, understand UTF-8 paths passed to it, etc.

These build process changes apply to all 3 ways that GNU Make can
be built for Windows:

1) configure
2) Basic.mk
3) build_w32.bat

When building with Visual Studio the resource compiler should always
be available.

When building with GCC or TCC, it depends on the availability of
'windres'.

If a resource compiler is not available, don't fail the build but
just proceed without the UTF-8 resource, effectively ignoring this
feature.

The UTF-8 resource only has an effect when GNU Make is running on a
minimum target version of Windows Version 1903 (May 2019 Update).
When the built GNU Make is running on an earlier version of Windows,
the embedded UTF-8 resource has no effect.

Code page information is added to --version output to tell users what
code pages are being used by any combination of GNU Make build (with
or without the UTF-8 resource) and Windows version that GNU Make is
running on (earlier than 1903 or not).

* README.git: Fix a typo.
* configure.ac: Search for windres and set WINDRES / HAVE_WINDRES.
* Makefile.am: Add manifest and resource files to EXTRA_DIST and
add a windres invocation to build them.
* build_w32.bat: Add support to build resource files.
* src/main.c (print_version): Add codepage info to Windows output.
* src/w32/utf8.manifest: Add a windres manifest file.
* src/w32/utf8.rc: Add a windres resource file.
* Basic.mk.template: Add support for building resource files.
* mk/Windows32.mk: Support windres resource files.
* .gitignore: Ignore TCC output directories.