Revise the thriftcheck error pattern (#82)
Revise the thriftcheck error pattern (#82)

More recent versions of thriftcheck use a more compliant GCC-style
output format which includes a space before the "severity" group.
This matches similar tools, like shellcheck.

This change adjusts the handler's pattern to parse this format in a
backwards-compatible way (even though backwards compatibility isn't
critical long-term as thriftcheck itself is close to its 1.0 release).
pinterest/arcanist-linters,pinterest/arcanist-linters