- Update compiler_flags.patch

- Update to 8.14.6:
* bad voice combine '3' when 3 voices and unison
* don't separate the accents from the notes by tuplets
* clash of tuplet numbers with accents
* bad time signature when C or C| and more value(s)
* warnings from clang static analysis
* bad music font selection when not defined by 'url(..)'
* bad vertical offset of "%%multicol new" when W: and %%begintext
* bad handling of fonts
* Add option flatbeamgracing that applies flat beams to grace notes only
* put the upper tuplets a bit closer to the notes