Slightly improve formatting of longer pipe statements.

The stronger binding of a string ending in :/= does not really make
sense if it is the only character.

Before:
llvm::outs() << aaaaaaaaaaaaaaaaaaaaaaaa
             << "=" << bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;

After:
llvm::outs() << aaaaaaaaaaaaaaaaaaaaaaaa << "="
             << bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@177075 91177308-0d34-0410-b5e6-96231b3b80d8