switch AddLineNumber to use a SmallString instead of sstream.  This
speeds up -emit-html on ted's testcase by 29% (.138 -> 0.107s) in a
release build.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@49767 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed