Fixes compiler warning
test-unicode.c:589:1: warning: ‘test_unicode_properties_lenient’ defined but not used
which didn't happen with autotools.
Reason it does with meson is that the setup for C was slightly wrong.
We would only add -DHAVE_CONFIG_H to cpp_args which is only valid when
compiling C++ code, but not plain C code, and many of these tests were
plain C.
Instead pass -DHAVE_CONFIG_H via add_project_arguments() and make sure
to set both c_args and cpp_args when building test executables.
Fixes https://github.com/harfbuzz/harfbuzz/issues/2257
...and supersede the configuration option uniscribe with gdi, as Uniscribe is
tightly tied to GDI. This means that enabling GDI would also mean enabling
Uniscribe.
Since Cairo's build system for Visual Studio does not generate pkg-config files
for us, look for cairo.h and cairo.lib manually if the pkg-config files cannot
be found.
Also look for cairo-ft more carefully: ensure that we have cairo-ft.h, and one
of its symbols can be found in the same cairo.lib that we previously found.
ICU's Visual Studio build files do not generate pkg-config files for us, unless
it is built with Cygwin instead of the project files. If pkg-config files for
ICU cannot be found, look for its headers and .lib manually.