branchmap: annotate constructor type for branchcache
This type signature is...big. But it's correct as far as I can tell,
and it detected a bug.
Differential Revision: https://phab.mercurial-scm.org/D7389
BasedOnStyle: LLVM
IndentWidth: 8
UseTab: ForIndentation
BreakBeforeBraces: Linux
AllowShortIfStatementsOnASingleLine: false
IndentCaseLabels: false
AllowShortBlocksOnASingleLine: false
AllowShortFunctionsOnASingleLine: false
IncludeCategories:
- Regex: '^<'
Priority: 1
- Regex: '^"'
Priority: 2