spacecheck: check long lines and repeat spaces, fix fallouts

Verify if lines are not longer than 192 characters. Also verify if lines
have less than 79 repeat spaces (and fix one fallout).

To improve readability by avoiding long lines and to prevent adding
overly long lines with text that may go unnoticed in an editor or diff
viewer.

In addition to pre-existing line length limits: 79 for C, 132 for CMake
sources.

Also:
- spacecheck: fix/harden allowlist regexes.
- spacecheck: tidy-up quotes and simplify escaping.
- spacecheck: allow folding strings with repeat spaces.
- GHA: fix a suppressed shellcheck warning.
- GHA/macos: simplify by dropping brew bundle.
- test1119.pl: precompile a regex.
- FAQ.md: delete very long link to a Windows 7/2008 support article
  that's lost it relevance.

Closes #21087

.github/workflows/linux-old.yml

@@ -69,7 +69,8 @@ jobs:
           sha256sum freexian-archive-keyring_2022.06.08_all.deb && dpkg -i freexian-archive-keyring_2022.06.08_all.deb
           echo 'deb http://deb.freexian.com/extended-lts stretch-lts main contrib non-free' | tee /etc/apt/sources.list.d/extended-lts.list
           apt-get -o Dpkg::Use-Pty=0 update
-          apt-get -o Dpkg::Use-Pty=0 install -y --no-install-suggests --no-install-recommends make automake autoconf libtool ninja-build gcc pkg-config libpsl-dev libzstd-dev zlib1g-dev libkrb5-dev libldap2-dev stunnel4
+          apt-get -o Dpkg::Use-Pty=0 install -y --no-install-suggests --no-install-recommends \
+            make automake autoconf libtool ninja-build gcc pkg-config libpsl-dev libzstd-dev zlib1g-dev libkrb5-dev libldap2-dev stunnel4
           # GitHub's actions/checkout needs newer glibc and libstdc++. The latter also depends on
           # gcc-8-base, but it does not actually seem used in our situation and is not available in
           # the main repo, so force the install.