When binding an lvalue to a reference, we always need to pop temporaries.

With this fix, and the other fixes committed today a make check-all with a clang-built LLVM now gives:

Expected Passes    : 6933
Expected Failures  : 46
Unsupported Tests  : 40
Unexpected Failures: 27

which means that we pass 99.96% of all tests :) The resulting 27 tests are all LLVMC tests and seem to be because of differences in the clang and gcc drivers.

llvm-svn: 95313