Rework InitPreprocessor to use a MacroBuilder class instead of pushing around
std::vectors.

- MacroBuilder wraps a raw_ostream so it can easily write to any buffer
  supported by raw_ostream.
- MacroBuilder's method take Twines for easy string concatenation (this was done
  with sprintf and temporary buffers before).
- Targets still use std::vector as they don't have access to the builder.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@93051 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed