svgtiny: create BUILDDIR before $(BUILDDIR)/src_colors.c

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
--- libsvgtiny-12121/src/Makefile.orig	2014-06-17 15:30:21.765311434 +0400
+++ libsvgtiny-12121/src/Makefile	2014-06-17 15:29:56.569909931 +0400
@@ -3,7 +3,7 @@
 
 SOURCES := $(SOURCES) $(BUILDDIR)/src_colors.c
 
-$(BUILDDIR)/src_colors.c: src/colors.gperf
+$(BUILDDIR)/src_colors.c: src/colors.gperf $(BUILDDIR)/stamp
 	$(VQ)$(ECHO) "   GPERF: $<"
 	$(Q)gperf --output-file=$@.tmp $<
 # Hack for GCC 4.2 compatibility (gperf 3.0.4 solves this properly)