[basisu] update to v1.50.0

[aminya]

Patches upstreamd here: BinomialLLC/basis_universal#383

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version.
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

[dg0yt]

For optional targets, it is sometimes less intrusive to only control build and install instead of adding conditions everywhere. i.e.

# not conditional; not modified
add_library(examples ...)
target_link_libraries(examples PRIVATE mainlib)

# only condition
if(EXAMPLES)
    install(TARGETS examples ...)
else()
    set_target_properties(examples PROPERTIES EXCLUDE_FROM_ALL 1)
endif()

[aminya]

Thanks for the tip. Here I went with the proper way as I did the same in the upstream PR.

[jimwang118]

Usage test passed on x64-windows triplet.