Fixes various problems with accounting for tabs in the original code.

We now count the original token's column directly when lexing the
tokens, where we already have all knowledge about where lines start.

Before this patch, formatting:
 void f() {
 \tg();
 \th();
 }
would incorrectly count the \t's as 1 character if only the line
containing h() was reformatted, and thus indent h() at offset 1.

llvm-svn: 189585