Skip whitespace when looking for a potential intended match.

Skip whitespace when looking for a potential intended match.
Before:

<stdin>:94:1: note: possible intended match here
 movsd 4096(%rsi), %xmm0
^

After:
<stdin>:94:2: note: possible intended match here
 movsd 4096(%rsi), %xmm0
 ^

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94847 91177308-0d34-0410-b5e6-96231b3b80d8