4c2766b (drm_mmap/drm_unmap) brought this error for every .c file that
was not #including config.h:
In file included from private.h:4:0,
from abi16.c:29:
../libdrm.h: In function 'drm_munmap':
../libdrm.h:81:4: error: size of unnamed array is negative
Signed-off-by: Rob Clark <robdclark@gmail.com>