tests/Makefile: not everyone has . in $PATH

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

tests/Makefile

@@ -5,7 +5,7 @@ T = $(wildcard t[0-9][0-9][0-9][0-9]-*.sh)
 all: $(T)
 
 $(T):
-	@$@
+	@./$@
 
 clean:
 	$(RM) -rf trash