Update installdeps to support CLANG64/CLANG32 MSYS2 targets.
cmake:
Set POLICY CMP0060 to NEW to not convert full lib paths, this is the
default.
Stop disabling ffmpeg on WIN32+i686.
On MSYS2+clang add windows import libs to CMAKE_PREFIX_PATH.
For static builds on MSYS2 append full paths for static libs for tiff,
jbig and lzma to FFMPEG_LIBRARIES.
Add -Wno-unused-command-line-argument to all CFLAGS/CXXFLAGS so that
clang does not warn about gcc-specific options.
Enable -march/-mtune optimizations by default instead of only for
UPSTREAM_RELEASE.
Update find_wx_util() to search suffixes for WIN32 and add the "static"
suffix for static builds.
Remove all linker flags from wxWidgets_LIBRARIES and translate all wx*
libs as well as jpeg, tiff, jbig lzma and expat to full .a paths for
static builds.
Disable strutil tests on MSYS2+clang, currently does not build.
Signed-off-by: Rafael Kitover <rkitover@gmail.com>