configure libgsm patch by (Justin Ruggles: jruggle, earthlink net)

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@4500 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

Makefile

@@ -69,6 +69,10 @@ ifeq ($(CONFIG_XVID),yes)
 EXTRALIBS+=-lxvidcore
 endif
 
+ifeq ($(CONFIG_LIBGSM),yes)
+EXTRALIBS+=-lgsm
+endif
+
 ifeq ($(CONFIG_DC1394),yes)
 EXTRALIBS+=-ldc1394_control -lraw1394
 endif