add r.buildvrt to Makefile

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@72764 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/Makefile

@@ -3,6 +3,7 @@ MODULE_TOPDIR = ..
 SUBDIRS = \
 	r.basins.fill \
 	r.buffer \
+	r.buildvrt \
 	r.carve \
 	r.category \
 	r.circle \