Replace DiagnosticClient::setLangOptions with {Begin,End}SourceFile, and clarify
invariants (diagnostics with source informations must occur between
{Begin,End}SourceFile).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86113 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed