ART: PathClassLoader for compiler

Use an actual PathClassLoader when compiling apps, instead of a
side structure and cutout.

This CL sets up a minimal object 'cluster' that recreates the Java
side of a regular ClassLoader such that the Class-Linker will
recognize it and use the internal native fast-path.

This CL removes the now unnecessary compile-time-classpath and
replaces it with a single 'compiling-the-boot-image' flag in the
compiler callbacks.

Note: This functionality is *only* intended for the compiler, as
the objects have not been completely initialized.

Bug: 19781184

Change-Id: I7f36af12dd7852d21281110a25c119e8c0669c1d
diff --git a/compiler/dex/quick_compiler_callbacks.h b/compiler/dex/quick_compiler_callbacks.h
index cdf71b6..56706e3 100644
--- a/compiler/dex/quick_compiler_callbacks.h
+++ b/compiler/dex/quick_compiler_callbacks.h
@@ -27,8 +27,9 @@
 class QuickCompilerCallbacks FINAL : public CompilerCallbacks {
   public:
     QuickCompilerCallbacks(VerificationResults* verification_results,
-                           DexFileToMethodInlinerMap* method_inliner_map)
-        : verification_results_(verification_results),
+                           DexFileToMethodInlinerMap* method_inliner_map,
+                           bool boot_image)
+        : CompilerCallbacks(boot_image), verification_results_(verification_results),
           method_inliner_map_(method_inliner_map) {
       CHECK(verification_results != nullptr);
       CHECK(method_inliner_map != nullptr);