build: fix the strip default for musl

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35389 3c298f89-4303-0410-b956-a3cf2f4a3e73

Config.in

@@ -515,7 +515,7 @@ menu "Global build settings"
 	choice
 		prompt "Binary stripping method"
 		default USE_STRIP   if EXTERNAL_TOOLCHAIN
-		default USE_STRIP   if USE_GLIBC || USE_EGLIBC
+		default USE_STRIP   if USE_GLIBC || USE_EGLIBC || USE_MUSL
 		default USE_SSTRIP
 		help
 		  Select the binary stripping method you wish to use.