CFLAGS currently takes care of two aspects of the build: optimisation
and debug symbols on one hand, the include path on the other. The
former should be overridable by users, the latter shouldn't.
This patch moves the include path flag to CPPFLAGS, which is
appropriate for pre-processor directives. This leaves CFLAGS with only
overridable flags.
Based on a patch by Roflcopter4:
https://github.com/joncampbell123/dosbox-x/pull/3850
Signed-off-by: Stephen Kitt <steve@sk2.org>
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
