It's cumbersome to maintain the build options twice, one time in the
configure script and one time in meson_options.txt. Thus let's add some
logic to the configure script to look at the meson_options.txt file
instead of handling every option twice.

Note: Unlike Paolo's earlier version (which can bee found on
https://patchew.org/QEMU/20210107140039.467969-1-pbonzini@redhat.com/ ),
this version only uses some lines of shell code to parse meson_options.txt
instead of adding an additional Python or Perl script. It's likely not
as robust as Paolo's version, but it's way smaller and has a way nicer
diffstat.

v2:
 - Improved shell code according to the suggestions of Eric
 - Split the vnc change into a separate patch
 - Add a comment to meson_options.txt in the new final patch

Thomas Huth (5):
  configure: Add the possibility to read options from meson_options.txt
  meson_options.txt: Switch the default value for the vnc option to
    'auto'
  configure: Remove options that can be handled via meson_options.txt
    instead
  configure: Get help text from meson_options.txt
  meson_options.txt: Document that "configure" reads this file, too

 configure         | 435 +++++++---------------------------------------
 meson_options.txt |   8 +-
 2 files changed, 65 insertions(+), 378 deletions(-)

-- 
2.27.0