surfman/drm: Makefile dependencies.
surfman/drm: Makefile dependencies.

Autotools needs the headers in SOURCES to handle rebuild dependencies
when a header changes.

Signed-off-by: Eric Chanudet <945795ca4030d561e78db98ba644d7fd3cee2cf0@ainfosec.com>

OpenXT/surfman,OpenXT/surfman,OpenXT/surfman