Use ', not `, for quoting output.

Use ', not `, for quoting output.

* build-aux/announce-gen (usage, sizes, print_news_deltas)
(print_changelog_deltas, get_tool_versions, main program):
* build-aux/git-version-gen:
* build-aux/gitlog-to-changelog (usage, parse_amend_file):
* build-aux/move-if-change (help):
* build-aux/useless-if-before-free (usage, main program):
* check-module (parse_module_file, usage)
(find_included_lib_files, check_module):
* lib/argmatch.c (main) [TEST]:
* lib/argp-help.c (_help):
* lib/getopt1.c (main) [TEST]:
* lib/git-merge-changelog.c (usage):
* lib/xstrtol-error.c (xstrtol_error):
* m4/alloca.m4 (_AC_LIBOBJ_ALLOCA):
* m4/argz.m4 (gl_FUNC_ARGZ):
* m4/bison.m4 (gl_BISON):
* m4/calloc.m4 (gl_FUNC_CALLOC_GNU):
* m4/extensions.m4 (AC_USE_SYSTEM_EXTENSIONS):
* m4/flexmember.m4 (AC_C_FLEXIBLE_ARRAY_MEMBER):
* m4/fpending.m4 (gl_PREREQ_FPENDING):
* m4/gc-random.m4 (gl_GC_RANDOM):
* m4/intl.m4 (gt_CHECK_DECL):
* m4/link-follow.m4 (gl_FUNC_LINK_FOLLOWS_SYMLINK):
* m4/longlong.m4 (AC_TYPE_LONG_LONG_INT)
(AC_TYPE_UNSIGNED_LONG_LONG_INT):
* m4/ls-mntd-fs.m4 (gl_LIST_MOUNTED_FILE_SYSTEMS):
* m4/lstat.m4 (gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK):
* m4/onceonly.m4 (AC_CHECK_FUNCS_ONCE):
* m4/posixver.m4 (gl_DEFAULT_POSIX2_VERSION):
* tests/test-dirname.c (main):
* tests/test-getpass.c (main):
* tests/test-iconvme.c (main):
* tests/test-parse-datetime.c (LOG):
* tests/test-xstrtoimax.sh:
* tests/test-xstrtol.sh:
* tests/test-xstrtoll.sh:
* tests/test-xstrtoumax.sh:
* tests/unigbrk/test-uc-is-grapheme-break.c (main):
* top/GNUmakefile (abort-due-to-no-makefile):
Quote 'like this', not `like this', as per the recent change to
the GNU coding standards.