Stop aligning trailing comments which are aligned with the next line.

Previously we would align:
f(); // comment
     // other comment
g();

Even if // other comment was at the start of the line. Now we do not
align trailing comments if they have been already aligned correctly
with the next line.

Thus,
f(); // comment
// other comment
g();
will not be changed, while:
f(); // comment
  // other commment
g();
will lead to the two trailing comments being aligned.

llvm-svn: 182577