util: Prevent glheader.h from including <windows.h> by defining APIENTRY

util: Prevent glheader.h from including <windows.h> by defining APIENTRY

When APIENTRY is not defined, GL/gl.h and GL/glext.h will automatically
include <windows.h>, so we save the macro APIENTRY by push_macro and then
define APIENTRY before include of GL/gl.h and GL/glext.h.
After that we use pop_macro to recover the previous macro again.

Because windows.h is not included by glheader.h, mesa/main/errors.c needs
to include <windows.h> directly to prevent the following error:
errors.c:98:10: error: implicit declaration of function 'OutputDebugStringA' [-Werror=implicit-function-declaration]
   98 |          OutputDebugStringA(buf);

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Acked-by: Brian Paul brianp@vmware.com
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19472>