flac: add universal option

Closes #19738.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
fltk: add universal option, build with --enable-shared

Closes #19771.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
fltk: add patch for issue with -lpng

https://trac.macports.org/browser/trunk/dports/aqua/fltk/files/patch-src-Makefile.diff

Signed-off-by: Jack Nagel <jacknagel@gmail.com>