hack Makefile to install .v files (for iris_options)

awk.Makefile

@@ -9,6 +9,11 @@
 	PROJECT=PIECES[2];
 }
 
+# Set the missing variable VFILES0 so that .v files are installed.
+/^VOFILES0=/ {
+	print "VFILES0=$(patsubst theories/%,%,$(filter theories/%,$(VFILES)))"
+}
+
 # Patch the uninstall target to work properly, and to also uninstall stale files.
 # Also see <https://coq.inria.fr/bugs/show_bug.cgi?id=4907>.
 /^uninstall:/ {