mesa: Rename "texturebarrier" source files to "barrier".

In preparation for collecting all pipeline barrier GL entry points
into a single source file.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
diff --git a/src/mesa/Makefile.sources b/src/mesa/Makefile.sources
index 472e767..3622760 100644
--- a/src/mesa/Makefile.sources
+++ b/src/mesa/Makefile.sources
@@ -24,6 +24,8 @@
 	main/atifragshader.h \
 	main/attrib.c \
 	main/attrib.h \
+	main/barrier.c \
+	main/barrier.h \
 	main/blend.c \
 	main/blend.h \
 	main/blit.c \
@@ -230,8 +232,6 @@
 	main/texstore.h \
 	main/textureview.c \
 	main/textureview.h \
-	main/texturebarrier.c \
-	main/texturebarrier.h \
 	main/transformfeedback.c \
 	main/transformfeedback.h \
 	main/uniform_query.cpp \