Fix pr4195: When iterating through predecessor blocks, break out of the loop
after finding the (unique) layout predecessor. Sometimes a block may be listed
more than once, and processing it more than once in this loop can lead to
inconsistent values for FtTBB/FtFBB, since the AnalyzeBranch method does not
clear these values. There's no point in continuing the loop regardless.
The testcase for this is reduced from the 2003-05-02-DependentPHI SingleSource
test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71536
91177308-0d34-0410-b5e6-
96231b3b80d8