Make ARM RegNames[] static like X86 (no ARM syms in X86-only build).

src/IceTargetLoweringARM32.h

 //===- subzero/src/IceTargetLoweringARM32.h - ARM32 lowering ----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 371 matching lines @@
 
   TargetARM32Features CPUFeatures;
   bool UsesFramePointer = false;
   bool NeedsStackAlignment = false;
   bool MaybeLeafFunc = true;
   size_t SpillAreaSizeBytes = 0;
   llvm::SmallBitVector TypeToRegisterSet[IceType_NUM];
   llvm::SmallBitVector ScratchRegs;
   llvm::SmallBitVector RegsUsed;
   VarList PhysicalRegisters[IceType_NUM];
-  static IceString RegNames[];
 
   /// Helper class that understands the Calling Convention and register
   /// assignments. The first few integer type parameters can use r0-r3,
   /// regardless of their position relative to the floating-point/vector
   /// arguments in the argument list. Floating-point and vector arguments
   /// can use q0-q3 (aka d0-d7, s0-s15). Technically, arguments that can
   /// start with registers but extend beyond the available registers can be
   /// split between the registers and the stack. However, this is typically
   /// for passing GPR structs by value, and PNaCl transforms expand this out.
   ///
@@ skipping 58 matching lines @@
 
 private:
   ~TargetHeaderARM32() = default;
 
   TargetARM32Features CPUFeatures;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGARM32_H