"Slang" no longer needs "--allow-rs-prefix" option. "Slang" now knows if a function
is in a system header file. If so, the function can be prefixed by "rs". Otherwise,
"rs" prefix is rightly disallowed. So, no more "allow-rs-prefix" hacking.

Change-Id: I8d5982cd6a75d465ffa6f98ca96941ae761117a2
diff --git a/core/definitions.mk b/core/definitions.mk
index 5262249..450b378 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -768,7 +768,6 @@
 $(hide) mkdir -p $(PRIVATE_RS_OUTPUT_DIR)/res/raw
 $(hide) mkdir -p $(PRIVATE_RS_OUTPUT_DIR)/src
 $(hide) $(SLANG) \
-  --allow-rs-prefix \
   -o $(PRIVATE_RS_OUTPUT_DIR)/res/raw \
   -p $(PRIVATE_RS_OUTPUT_DIR)/src \
   $(foreach inc,$(PRIVATE_RS_INCLUDES),$(addprefix -I , $(inc))) \