egl: add missing glvnd entrypoint for EGL_ANDROID_blob_cache

egl: add missing glvnd entrypoint for EGL_ANDROID_blob_cache

Fixes dEQP-EGL.functional.get_proc_address.extension.egl_android_blob_cache
on builds with glvnd enabled.

Fixes: 6f5b57093b3462a54e9c7 "egl: add support for EGL_ANDROID_blob_cache"
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
(cherry picked from commit c9733649670243a1a6eb7ca2c376bd27960f8d8a)

Squashed with commit:

egl: fix bad rebase

I screwed up a rebase over a refactor and didn't notice locally because
the uncommitted refactor hid the issue.

Fixes: c9733649670243a1a6eb "egl: add missing glvnd entrypoint for EGL_ANDROID_blob_cache"
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
(cherry picked from commit 2b2f790e594cde3aa0d4dcebafc9a072651cd62a)