fix build dependency

package/gcc/Makefile

@@ -8,7 +8,7 @@ PKG_DESCR:=		GNU compiler collection
 PKG_SECTION:=		lang
 PKG_OPTS:=		noremove
 PKG_DEPENDS:=		libmpc libgmp mpfr
-PKG_BUILDDEP:=		mpc gmp mpfr
+PKG_BUILDDEP:=		libmpc gmp mpfr
 
 PKG_TARGET_DEPENDS:=	!ag241