[NFC] As part of using inclusive language within the llvm project, this patch replaces `m_master` in `ASTImporterDelegate` with `m_main`. Reviewed By: teemperor, clayborg Differential Revision: https://reviews.llvm.org/D113720
[NFC] As part of using inclusive language within the llvm project, this patch replaces `m_master` in `ASTImporterDelegate` with `m_main`. Reviewed By: teemperor, clayborg Differential Revision: https://reviews.llvm.org/D113720