Revert "Make clang the default compiler on host."

This reverts commit 87f8b4cf0c1d6aab3eb5d1e99cc4e7cf175ef772.

Change-Id: I91a513042f0f9cf66288a296ad4a3b5da7830c7b
diff --git a/compiler/driver/compiler_driver.h b/compiler/driver/compiler_driver.h
index 817da17..12463a9 100644
--- a/compiler/driver/compiler_driver.h
+++ b/compiler/driver/compiler_driver.h
@@ -564,11 +564,8 @@
   class ProfileData {
    public:
     ProfileData() : count_(0), method_size_(0), percent_(0) {}
-    ProfileData(const std::string& method_name, uint32_t count, uint32_t method_size, double percent) :
+    ProfileData(std::string method_name, uint32_t count, uint32_t method_size, double percent) :
       method_name_(method_name), count_(count), method_size_(method_size), percent_(percent) {
-      // TODO: currently method_size_ and count_ are unused.
-      UNUSED(method_size_);
-      UNUSED(count_);
     }
 
     bool IsAbove(double v) const { return percent_ >= v; }