Merge from origin/emacs-26

Merge from origin/emacs-26

2670cbf (origin/emacs-26) ; * configure.ac: Remove outdated comment (...
3b71bef admin.el: respect environment settings for makeinfo etc
3764ab4 * etc/PROBLEMS: New entry about GTK+ 3 crash with some X serv...
9d61344 Index profiler commands in elisp manual
f088817 Fix math-imaginary-i check
fca935e ; Let pre-commit git hook check merged in changes (Bug#29197)
fe06fcc Avoid infinite hscrolling loops when line numbers are displayed
63e59c8 Avoid crashes in malformed defvar
785682c * configure.ac (emacs_config_features): Add GLIB, XDBE, XIM.
2695b7e * configure.ac: Doc fixes related to --with-xim.
d0d162c Small checkdoc quoting fix (bug#32546)

Conflicts:
	configure.ac