Merge from origin/emacs-27

Merge from origin/emacs-27

a2b07f9f11 (origin/emacs-27) ; * etc/NEWS: Explain how to get back ol...
b468b3d1ff Fix a recent documentation change
1ab766fd58 Fix last change
ecfe633993 * lisp/tab-bar.el: Last-minute changes.
c1ce9fa7f2 * lisp/subr.el (cancel-change-group): Fix bug#39680
ef5744a988 Improve docs for horizontal scrolling with mouse and touch...
1bc3fa0bd0 * lisp/emacs-lisp/package.el (package-install): Fix typo i...
4537976afd Port .gdbinit to clang with -gdwarf-4
0883c800a0 Simplify rx example in manual
a695189248 ; * etc/NEWS: Fix typo.

# Conflicts:
#	etc/NEWS