graphics/pngcrush: Mark BROKEN and set expiration date to 2024-02-29

Fails to build with libpng 1.6.41 due to usage of undocumented feature to
disable Adler32 checksums.
Last release in 2017 and dead upstream, redirect users to graphics/oxipng
or graphics/pngquant

Reference:
https://github.com/pnggroup/libpng/commit/269b753496180cdb3082d87b0cd907905593dee5

PR:		276649
Reviewed by:	Anton Saietskii <vsasjason@gmail.com> (maintainer)