winsys/etnaviv: automake: introduce Makefile.sources

... and list the public header within it.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/src/gallium/winsys/etnaviv/drm/Makefile.am b/src/gallium/winsys/etnaviv/drm/Makefile.am
index 995b709..ed04d95 100644
--- a/src/gallium/winsys/etnaviv/drm/Makefile.am
+++ b/src/gallium/winsys/etnaviv/drm/Makefile.am
@@ -20,6 +20,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 # DEALINGS IN THE SOFTWARE.
 
+include Makefile.sources
 include $(top_srcdir)/src/gallium/Automake.inc
 
 AM_CFLAGS = \
@@ -29,4 +30,4 @@
 
 noinst_LTLIBRARIES = libetnavivdrm.la
 
-libetnavivdrm_la_SOURCES = etnaviv_drm_winsys.c
+libetnavivdrm_la_SOURCES = $(C_SOURCES)
diff --git a/src/gallium/winsys/etnaviv/drm/Makefile.sources b/src/gallium/winsys/etnaviv/drm/Makefile.sources
new file mode 100644
index 0000000..f338b08
--- /dev/null
+++ b/src/gallium/winsys/etnaviv/drm/Makefile.sources
@@ -0,0 +1,3 @@
+C_SOURCES := \
+	etnaviv_drm_public.h \
+	etnaviv_drm_winsys.c