Add to the split module utility an SCC based method which allows not to...

    Add to the split module utility an SCC based method which allows not to globalize any local variables.
    
    Summary:
    Currently llvm::SplitModule as the first step globalizes all local objects, which might not be desirable in some scenarios.
    This change adds a new flag to llvm::SplitModule that uses SCC approach to search for a balanced partition without the need to externalize symbols.
    Such partition might not be possible or fully balanced for a given number of partitions, and is a function of the module properties (global/local dependencies within the module).
    
    Joint development Tobias Edler von Koch (tobias@codeaurora.org) and Sergei Larin (slarin@codeaurora.org)
    
    Subscribers: llvm-commits, joker.eph
    
    Differential Revision: http://reviews.llvm.org/D16124

llvm-svn: 258083