Merge "BuildSystem: Really do not pass unknown-warning options to the compiler."

third-party/pjproject/patches/user.mak

 
-NUBSV := $(shell gcc -Wno-unused-but-set-variable -o /dev/null -xc -c - </dev/null 2>/dev/null && echo -Wno-unused-but-set-variable)
+NUBSV := $(shell ${CC} -Wno-unused-but-set-variable -Werror -o /dev/null -xc -c - </dev/null 2>/dev/null && echo -Wno-unused-but-set-variable)
 
 CFLAGS += -fPIC $(NUBSV) -Wno-unused-variable -Wno-unused-label -Wno-unused-function -Wno-strict-aliasing