gcc: depend on libzstd

Signed-off-by: W. Michael Petullo <mike@flyn.org>
(cherry picked from commit 8e0bc54fcd)

devel/gcc/Makefile

@@ -55,7 +55,7 @@ define Package/gcc
   CATEGORY:=Development
   TITLE:=gcc
   MAINTAINER:=W. Michael Petullo <mike@flyn.org>
-  DEPENDS:= +binutils +libstdcpp @!arc
+  DEPENDS:= +binutils +libstdcpp +libzstd @!arc
   MENU:=1
 endef