pkg: oonf_api, disable compiler errors if toolchain llvm

    - set no-keyword-macro
    - set no-parentheses-equality

pkg/oonf_api/Makefile.include

 INCLUDES += -I$(PKGDIRBASE)/oonf_api/src-api
 
-ifeq ($(shell uname -s),Darwin)
-	CFLAGS += -Wno-reserved-id-macro -Wno-keyword-macro
+ifeq ($(TOOLCHAIN), llvm)
+    CFLAGS += -Wno-keyword-macro -Wno-parentheses-equality
 endif