Fix stack misalignment issues.

- Call ABI_AlignStack even on x86-64.

- Have ABI_AlignStack respect the difference in current alignment
  between the root JIT function, which has a prolog, and
  ProtectFunction thunks, which do not.  This was causing many games
  to crash on start on OS X.  Since this might otherwise mean changing
  the stack pointer before every call...

- Have one prolog/epilog function rather than two (one of which
  definitely did not do what it was thought to do), and make it
  actually work like a normal one, so that the stack frame shows up
  properly in the debugger.  There should be no performance impact.

Source/Core/VideoCommon/Src/VertexLoader.cpp

@@ -217,7 +217,7 @@ void VertexLoader::CompileVertexTranslator()
 		PanicAlert("Trying to recompile a vertex translator");
 
 	m_compiledCode = GetCodePtr();
-	ABI_EmitPrologue(4);
+	ABI_PushAllCalleeSavedRegsAndAdjustStack();
 
 	// Start loop here
 	const u8 *loop_start = GetCodePtr();
@@ -499,7 +499,8 @@ void VertexLoader::CompileVertexTranslator()
 #endif
 
 	J_CC(CC_NZ, loop_start, true);
-	ABI_EmitEpilogue(4);
+	ABI_PopAllCalleeSavedRegsAndAdjustStack();
+	RET();
 #endif
 	m_NativeFmt->Initialize(vtx_decl);
 }