Build failure with MSVC
After a few patches to get meson subproject fallbacks working, gtk master fails to build on Windows with MSVC:
FAILED: gdk/libgdk.a.p/gdkglcontext.c.obj
"cl" "-Igdk\libgdk.a.p" "-Igdk" "-I..\gdk" "-I." "-I.." "-I..\gdk\x11" "-Isubprojects\gdk-pixbuf" "-I..\subprojects\gdk-pixbuf" "-Isubprojects\glib" "-I..\subprojects\glib" "-Isubprojects\glib\glib" "-I..\subprojects\glib\glib" "-Isubprojects\proxy-libintl" "-I..\subprojects\proxy-libintl" "-Isubprojects\glib\gobject" "-I..\subprojects\glib\gobject" "-Isubprojects\glib\gmodule" "-I..\subprojects\glib\gmodule" "-Isubprojects\glib\gio" "-I..\subprojects\glib\gio" "-Isubprojects\cairo\src" "-I..\subprojects\cairo\src" "-Isubprojects\pango\pango" "-I..\subprojects\pango\pango" "-Isubprojects\fribidi" "-I..\subprojects\fribidi" "-Isubprojects\fribidi\lib" "-I..\subprojects\fribidi\lib" "-Isubprojects\fribidi\gen.tab" "-I..\subprojects\fribidi\gen.tab" "-Isubprojects\harfbuzz\src" "-I..\subprojects\harfbuzz\src" "-I..\subprojects\freetype2\include" "-Isubprojects\zlib-1.2.11" "-I..\subprojects\zlib-1.2.11" "-Isubprojects\libpng-1.6.35" "-I..\subprojects\libpng-1.6.35" "-Isubprojects\fontconfig" "-I..\subprojects\fontconfig" "-I..\subprojects\expat-2.2.5\lib" "-Isubprojects\cairo\util\cairo-gobject" "-I..\subprojects\cairo\util\cairo-gobject" "-Isubprojects\graphene\include" "-I..\subprojects\graphene\include" "-Isubprojects\libepoxy\include" "-I..\subprojects\libepoxy\include" "-Isubprojects\libepoxy\src" "-I..\subprojects\libepoxy\src" "-Isubprojects\pango" "-I..\subprojects\pango" "-Isubprojects\gdk-pixbuf\gdk-pixbuf" "-Isubprojects\libepoxy\include\epoxy" "-Igtk\css" "/MD" "/nologo" "/showIncludes" "/W2" "/O2" "/Ob1" "/Zi" "-DG_LOG_USE_STRUCTURED=1" "-DGLIB_MIN_REQUIRED_VERSION=GLIB_VERSION_2_64" "-DGLIB_MAX_ALLOWED_VERSION=GLIB_VERSION_2_66" "-DGTK_VERSION=\"3.99.3\"" "-D_GNU_SOURCE" "-DG_ENABLE_DEBUG" "-utf-8" "-DGTK_COMPILATION" "-DG_LOG_DOMAIN=\"Gdk\"" "-D_USE_MATH_DEFINES" "-utf-8" "/Fdgdk\libgdk.a.p\gdkglcontext.c.pdb" /Fogdk/libgdk.a.p/gdkglcontext.c.obj "/c" ../gdk/gdkglcontext.c
../gdk/gdkglcontext.c(1023): error C2440: 'function': cannot convert from 'void (__cdecl *)(GLenum,GLenum,GLuint,GLenum,GLsizei,const GLchar *,const void *)' to 'GLDEBUGPROC'
../gdk/gdkglcontext.c(1023): warning C4024: 'epoxy_glDebugMessageCallback': different types for formal and actual parameter 1