Setting a breakpoint on `<symbol> + <offset>` used to work until
`2c76e88e9eb284d17cf409851fb01f1d583bb22a`, where this regex was
reworked. Now we only accept `<symbol>+ <offset>` or
`<symbol>+<offset>`.
This patch fixes the regression by adding yet another `[[:space:]]*`
component to the regex.
One could probably simplify the regex (or even replace the regex by just
calling the relevent `consumeXXX` APIs on `llvm::StringRef`). Though I
left that for the future.
rdar://130780342
1608fe8d56