suite make: specify gawk

broken for e.g. nawk

TODO: fix to work with any awk or replace awk script with something else
(e.g. separate crate with build.rs?)

tests/suite/Makefile

@@ -20,7 +20,7 @@ mod.rs: ${TEST_RS}
 	done
 
 .test.rs:
-	awk -fgen.awk $< > $@
+	gawk -fgen.awk $< > $@
 
 clean:
 	rm -f *.rs