Added override directive to CXXFLAGS for Synology builds in make-linux.mk

make-linux.mk

@@ -77,7 +77,7 @@ ifeq ($(ZT_QNAP), 1)
 endif
 
 ifeq ($(ZT_SYNOLOGY), 1)
-	CXXFLAGS+=-fPIC
+	override CXXFLAGS+=-fPIC
         override DEFS+=-D__SYNOLOGY__
 endif