Now that -loop-idiom uses TargetLibraryInfo properly, it doesn't

need to be pulled out of the pass manager when the user specifies 
-fno-builtin.  It can intelligently determine which libcalls to
optimize based on what is enabled in TargetLibraryInfo.  This 
allows -fno-builtin-foo to work someday.

llvm-svn: 125981