Entry point clean up.

Create set of entry points needed for image methods to avoid fix-up at load time:
 - interpreter - bridge to interpreter, bridge to compiled code
 - jni - dlsym lookup
 - quick - resolution and bridge to interpreter
 - portable - resolution and bridge to interpreter

Fix JNI work around to use JNI work around argument rewriting code that'd been
accidentally disabled.
Remove abstact method error stub, use interpreter bridge instead.
Consolidate trampoline (previously stub) generation in generic helper.
Simplify trampolines to jump directly into assembly code, keeps stack crawlable.
Dex: replace use of int with ThreadOffset for values that are thread offsets.
Tidy entry point routines between interpreter, jni, quick and portable.

Change-Id: I52a7c2bbb1b7e0ff8a3c3100b774212309d0828e
(cherry picked from commit 848871b4d8481229c32e0d048a9856e5a9a17ef9)
diff --git a/compiler/dex/quick/x86/target_x86.cc b/compiler/dex/quick/x86/target_x86.cc
index 2c9b3c8..699f3ae 100644
--- a/compiler/dex/quick/x86/target_x86.cc
+++ b/compiler/dex/quick/x86/target_x86.cc
@@ -524,7 +524,7 @@
 }
 
 // Not used in x86
-int X86Mir2Lir::LoadHelper(int offset) {
+int X86Mir2Lir::LoadHelper(ThreadOffset offset) {
   LOG(FATAL) << "Unexpected use of LoadHelper in x86";
   return INVALID_REG;
 }