* src/dispnew.c (add_window_display_history) [GLYPH_DEBUG]:
Remove redundant quotes.
* src/doc.c (uLSQM, uRSQM): New macros.
* src/doc.c (Fsubstitute_command_keys):
* src/syntax.c (Finternal_describe_syntax_value): Follow the user
preference for quotes rather than hardcoding the ‘grave’ style.
* src/regex.c (PUSH_FAILURE_POINT, POP_FAILURE_POINT)
(re_match_2_internal) [DEBUG]: In debugging output, quote C
strings with "...", not `...'.