linker: Switch to clang

x86_64 gcc exports malloc/free and co functions because they
are defined with visibility "default" somewhere in gcc builtins;
and vector d-tors for some reason. Switching to clang fixes
this problem.

Bug: http://b/24785482
Change-Id: I741503b4b446523e7ff3fb16de13ed99991fd0c0
diff --git a/linker/Android.mk b/linker/Android.mk
index 585a738..8be53a1 100644
--- a/linker/Android.mk
+++ b/linker/Android.mk
@@ -2,7 +2,9 @@
 
 include $(CLEAR_VARS)
 
-LOCAL_SRC_FILES:= \
+LOCAL_CLANG := true
+
+LOCAL_SRC_FILES := \
     debugger.cpp \
     dlfcn.cpp \
     linker.cpp \