implement the null function for the Mips32 subzero compiler

src/IceInstMIPS32.def

 //===- subzero/src/IceInstMIPS32.def - X-Macros for MIPS32 insts --*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines properties of MIPS32 instructions in the form of x-macros.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICEINSTMIPS32_DEF
 #define SUBZERO_SRC_ICEINSTMIPS32_DEF
 
 // NOTE: PC and SP are not considered isInt, to avoid register allocating.
-// TODO (reed kotler). This needs to be scrubbed and is a placeholder to get
+// TODO(reed kotler). This needs to be scrubbed and is a placeholder to get
 // the Mips skeleton in.
 //
 #define REGMIPS32_GPR_TABLE                                                    \
   /* val, encode, name, scratch, preserved, stackptr, frameptr, isInt, isFP */ \
   X(Reg_ZERO,     = 0,          "zero",  0, 0, 0, 0, 0, 0)                     \
   X(Reg_AT,       = Reg_ZERO + 1,   "at",    1, 0, 0, 0, 1, 0)                 \
   X(Reg_V0,       = Reg_ZERO + 2,   "v0",    1, 0, 0, 0, 1, 0)                 \
   X(Reg_V1,       = Reg_ZERO + 3,   "v1",    1, 0, 0, 0, 1, 0)                 \
   X(Reg_A0,       = Reg_ZERO + 4,   "a0",    1, 0, 0, 0, 1, 0)                 \
   X(Reg_A1,       = Reg_ZERO + 5,   "a1",    1, 0, 0, 0, 1, 0)                 \
@@ skipping 43 matching lines @@
 #define REGMIPS32_TABLE_BOUNDS                                                 \
   /* val, init */                                                              \
   X(Reg_GPR_First, = Reg_ZERO)                                                 \
   X(Reg_GPR_Last,  = Reg_RA)
 //define X(val, init)
 
 // TODO(reed kotler): add condition code tables, etc.
 
 
 #endif // SUBZERO_SRC_ICEINSTMIPS32_DEF