Merge from origin/emacs-27

9f08524748 (origin/emacs-27) Fix broken regexps
1d10885763 ; spelling and comment fix
614203bc80 ; make change-history-commit
28399e585e * Makefile.in (PREFERRED_BRANCH): Now emacs-27.
62afbc513a Fix bug when visiting euc-jp-encoded directories
a2c4eeeecd Clarify when fixnums are used.
4e5ac4b0c6 Reorder discussion of integer basics
f765aad28b Make OMake support slightly less expensive (bug#39595)
39410cfc5a Speed up 'msft' and 'watcom' compilation error regexps
96a269d045 Speed up 'maven' compilation error message regexp
efc9d4fe3e Amend c-backward-sws better to handle multiline block comm...

diff --cc src/fileio.c
Simple merge