Function::getNumBlockIDs() should be used instead of Function::size() to set the...

Function::getNumBlockIDs() should be used instead of Function::size() to set the upper limit on the block IDs since basic blocks might get removed (simplified away) after being initially numbered. Plus the test case, in which SelectionDAGBuilder::visitBr() calls llvm::MachineFunction::removeFromMBBNumbering(), which introduces the hole in numbering leading to an assert in llc (prior to the fix).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133113 91177308-0d34-0410-b5e6-96231b3b80d8