This commit improves bugpoints speed. On my G4 this changed caused kimwitu++...

This commit improves bugpoints speed. On my G4 this changed caused kimwitu++ to run through bugpoint in 1091.15 seconds (user + system time). The time it took to run this on my G4 before I made these changes is 1420.82 seconds (user + system time). This is a speedup of about 5.5 minutes.

This is faster because SplitFunctionsOutOfModule no longer calls Clone Module and then removes the functions it doesnt want from the module returned. Instead it creates a module and copies over the specified functions, making changes to the new and old module where neccessary. This reduces the memory demand.

llvm-svn: 29379