scangobj: revert the recent shlex changes
This reverts the following commits:
e37b083e Add a comment explaining previous change bdd4b1b3 scangobj: keep quotes when splitting with shlex
Python shlex.split itself isn't broken. It can properly handles arguments with quote characters as long as it is quoted correctly with functions such as shlex.quote. However, gnome.gtkdoc function in meson 0.48 doesn't do it correctly. It joins all arguments with spaces without quoting these arguments first, causing quotes in arguments themselves to be removed when it is processed by shlex.split.
The meson bug described above is fixed on the master branch before the shlex workaround committed to gtk-doc, so the workaround was, in fact, never really needed. Furthermore, the workaround causes gtkdoc-scangobj to interpret the command line differently with the shell, making it harder to use correctly and break builds when arguments are properly quoted with the rules of shell.
This fixes gtk-doc builds for at-spi2-core and WebKitGTK+.