MC should use cache directory cache/ as oBCC does.

Use std::string in constructing cache path above.

Change-Id: I02c478a7513ac87af07357137f56a42fe4615bc2
diff --git a/lib/ExecutionEngine/Compiler.h b/lib/ExecutionEngine/Compiler.h
index ba32a28..597618f 100644
--- a/lib/ExecutionEngine/Compiler.h
+++ b/lib/ExecutionEngine/Compiler.h
@@ -118,7 +118,7 @@
 
     CodeEmitter *createCodeEmitter();
 
-    int getFilePath(char *ObjectPath);
+    bool getObjPath(std::string &objPath);
 
     llvm::Module *parseBitcodeFile(llvm::MemoryBuffer *MEM);