Add a bit of lazy evaluation to PopulateCompilationGraph().

Only the tools that are mentioned in the compilation graph definition
are now inserted by PopulateCompilationGraph(). This should cut down
plugin loading time a little.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59097 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed