maint: fix typos in comments and ChangeLog

maint: fix typos in comments and ChangeLog

Culprits identified and fixed mostly automatically using these commands:
git ls-files | misspellings -f - |grep -v '^ERROR:' |perl -pe \
's/^(.*?)\[(\d+)\]: (\w+) -> "(.*?)"$/sed -i '\''${2}s!$3!$4!'\'' $1/'
using http://github.com/lyda/misspell-check
* ChangeLog: Fix typos.
* doc/solaris-versions: Likewise.
* lib/regexec.c (re_search_stub): Likewise.
* m4/mmap-anon.m4 (gl_FUNC_MMAP_ANON): Likewise.