Implement the "setIncludePaths" and "setSymbolDefines" interface methods.

Implement the "setIncludePaths" and "setSymbolDefines" interface methods.
Revise token substitution to be a little faster.
Clean up exception throwing, make sure its always a std::string.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16116 91177308-0d34-0410-b5e6-96231b3b80d8