[cmake] Don't fail if brotli is missing (#56894).

The libs which cmake controls are commented out at

  include/freetype/config/ftoption.h

and cmake un-comment each enabled library, but the brotli option was
not commented out, therefore `FT_CONFIG_OPTION_USE_BROTLI' remained
defined even if brotli was missing/disabled/etc.

Comment it such that cmake can control it, which means leaving it
undefined if brotli is missing.

* include/freetype/config/ftoption.h: Fix typo.
2 files changed