Tested with
./weston-simple-dmabuf-drm
./weston-simple-dmabuf-drm --import-immediate=1
./weston-simple-dmabuf-drm --y-inverted=1
(and combinations)
Supports only single plane XRGB dmabufs for now.
Due to the strstr prefix match EGL_EXT_foo would be incorrectly matched
if EGL_EXT_foobar would be available but not foo.
This doesn't matter for the currently checked extensions but will matter
for EGL_EXT_image_dma_buf_import_modifiers vs
EGL_EXT_image_dma_buf_import
Code borrowed from weston