Move the llvm-gcc warning from HOST_darwin-x86.mk to main.mk

Bug: 6754632
So the warning won't show up when you run lunch.
Now the warning only shows when you do a clean build.

Change-Id: I7876da783f059d390f0072df37d3ab0291589eb7
diff --git a/core/main.mk b/core/main.mk
index 3d8d6e0..3337a8a 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -152,6 +152,18 @@
 $(error stop)
 endif
 
+ifeq (darwin,$(HOST_OS))
+GCC_REALPATH = $(realpath $(shell which gcc))
+ifneq ($(findstring llvm-gcc,$(GCC_REALPATH)),)
+  # Using LLVM GCC results in a non functional emulator due to it
+  # not honouring global register variables
+  $(warning ****************************************)
+  $(warning * gcc is linked to llvm-gcc which will *)
+  $(warning * not create a useable emulator.       *)
+  $(warning ****************************************)
+endif
+endif
+
 $(shell echo 'VERSIONS_CHECKED := $(VERSION_CHECK_SEQUENCE_NUMBER)' \
         > $(OUT_DIR)/versions_checked.mk)
 endif