Format */& as binary operator if followed by a unary operator.

This fixes llvm.org/PR14687.
Also fixes segfault for lines starting with * or &.

Before:
a *~b;
*a = 1;  // <- this segfaulted

After:
a * ~b;
*a = 1;  // no segfault :-)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171396 91177308-0d34-0410-b5e6-96231b3b80d8