More MIPS fixes. Many run-test tests pass.

Run-test tests 001-043 work, including 003-omnibus-opcodes. 044 is
proxy, which is still broken.

Changes made:
- Fixed argument marshalling of FP values for calls to helper functions
  in the compiler.
- Fixed CheckCast compilation's mistaken use of rARG0 instead of rRET0.
- Fixed conversion calls to marshall FP arguments properly.
- Created named values for FP args, though they differ in MIPS only.
- Fixed assembly to always use T9 to hold code pointer to jump to.
- Fixed proxy offset values.

Change-Id: If121db322683a307e5a1016210f4f73283aa817c
diff --git a/src/compiler/codegen/mips/MipsLIR.h b/src/compiler/codegen/mips/MipsLIR.h
index 5077c9f..4b7da55 100644
--- a/src/compiler/codegen/mips/MipsLIR.h
+++ b/src/compiler/codegen/mips/MipsLIR.h
@@ -301,6 +301,10 @@
 #define rARG1 r_ARG1
 #define rARG2 r_ARG2
 #define rARG3 r_ARG3
+#define rFARG0 r_FARG0
+#define rFARG1 r_FARG1
+#define rFARG2 r_FARG2
+#define rFARG3 r_FARG3
 #define rRET0 r_RESULT0
 #define rRET1 r_RESULT1
 #define rINVOKE_TGT r_T9