Move frameworks/compile/slang off AndroidConfig.h.

Change-Id: I07e8bcde8e783712552f0029883a32fb93359a0c
diff --git a/llvm-rs-cc.cpp b/llvm-rs-cc.cpp
index 905f2e7..1a89d62 100644
--- a/llvm-rs-cc.cpp
+++ b/llvm-rs-cc.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/Signals.h"
 #include "llvm/Target/TargetMachine.h"
 
+#include "os_sep.h"
 #include "rs_cc_options.h"
 #include "slang.h"
 #include "slang_assert.h"