switch from using a vector to a smallvector for macro replacement tokens
This speeds up parsing carbon.h by 3.3% by avoiding some malloc traffic for 
small macros.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@39861 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed