When we're performing tentative parsing to determine whether the

parser is looking at a declaration or an expression, use a '=' to
conclude that we are parsing a declaration.

This is wrong. However, our previous approach of finding a comma after
the '=' is also wrong, because the ',' could be part of a
template-argument-list. So, for now we're going to use the same wrong
heuristic as GCC and Visual C++, because less real-world code is
likely to be broken this way. I've opened PR7655 to keep track of our
wrongness; note also the XFAIL'd test.

Fixes <rdar://problem/8193163>.

llvm-svn: 108459