Remove all TARGET_[ARM|X86|MIPS] #ifdefs

Two steps forward, one step back towards elimination of the
"#include" build model for target-specific compilers.  This CL
does some restructuring to eliminate all of the TARGET_xxx #ifdefs
and convert them to run-time tests.

Considerable work is still required to fully eliminate the multiple
builds.  In particular, much of the "common" codegen code relies on
macros defined by the target-specific [Arm|X86|Mips]Lir.h include file.

Next step is more restructuring to better isolate target-independent
code generation code.

Change-Id: If6efbde65c48031a48423344d8dc3e2ff2c4ad9d
diff --git a/src/compiler/codegen/RallocUtil.cc b/src/compiler/codegen/RallocUtil.cc
index 8fa110a..4848a59 100644
--- a/src/compiler/codegen/RallocUtil.cc
+++ b/src/compiler/codegen/RallocUtil.cc
@@ -14,13 +14,7 @@
  * limitations under the License.
  */
 
-/*
- * This file contains register alloction support and is intended to be
- * included by:
- *
- *        Codegen-$(TARGET_ARCH_VARIANT).c
- *
- */
+/* This file contains register alloction support. */
 
 #include "../CompilerUtility.h"
 #include "../CompilerIR.h"