Add source level deprecation warning disabling to certain tests/utils

[senhuang42]

As title. This adds the macro to fuzzer, zstreamtest, fullbench, and Pzstd.

Also adds thread_dep target to fuzzer in meson build, and -Wno-deprecated-declarations to the pzstd target in meson. For some reason, including the deprecate macro isn't sufficient in Pzstd.h

I think this is all of them.

[Cyan4973]

For some reason, including the deprecate macro isn't sufficient in Pzstd.h

That might be because zstd.h is included from Options.h too ?

[senhuang42]

I have verified that this now builds locally. Still, there is the remaining question of what to do with all the warnings -Wdocumentation -Wcomment.