grep: add MULTIREV support to --allfiles flag
This patch facilitates passing multiple revisions with all-files flag.
It's assumed that if you are passing multiple revisions to --allfiles,
you want hits from all of them.
Differential Revision: https://phab.mercurial-scm.org/D3976
BasedOnStyle: LLVM
IndentWidth: 8
UseTab: ForIndentation
BreakBeforeBraces: Linux
AllowShortIfStatementsOnASingleLine: false
IndentCaseLabels: false
AllowShortBlocksOnASingleLine: false
AllowShortFunctionsOnASingleLine: false
IncludeCategories:
- Regex: '^<'
Priority: 1
- Regex: '^"'
Priority: 2