Made GetClangTargetCPU() const.

[jmajors]

Summary

It does not change members or call non-const members.
HostInfo::GetArchitecture() returns a const object ref (maybe others?),
which can't access the non-const function.

lldb/trunk/include/lldb/Core/ArchSpec.h

public:
 
   //------------------------------------------------------------------
   /// Returns a string representing current architecture as a target CPU
   /// for tools like compiler, disassembler etc.
   ///
   /// @return A string representing target CPU for the current
   ///         architecture.
   //------------------------------------------------------------------
-  std::string GetClangTargetCPU();
+  std::string GetClangTargetCPU() const;
 
   //------------------------------------------------------------------
   /// Return a string representing target application ABI.
   ///
   /// @return A string representing target application ABI.
   //------------------------------------------------------------------
   std::string GetTargetABI() const;
 

lldb/trunk/source/Core/ArchSpec.cpp

if (IsMIPS()) {
     else if (elf_abi == "n32")
       flag |= ArchSpec::eMIPSABI_N32;
     else if (elf_abi == "o32")
       flag |= ArchSpec::eMIPSABI_O32;
   }
   SetFlags(flag);
 }
 
-std::string ArchSpec::GetClangTargetCPU() {
+std::string ArchSpec::GetClangTargetCPU() const {
   std::string cpu;
   const llvm::Triple::ArchType machine = GetMachine();
 
   if (machine == llvm::Triple::mips || machine == llvm::Triple::mipsel ||
       machine == llvm::Triple::mips64 || machine == llvm::Triple::mips64el) {
     switch (m_core) {
     case ArchSpec::eCore_mips32:
     case ArchSpec::eCore_mips32el: