Add PS Vita port.

Thanks to Anton Stenmark.
Merge branch 'master' into v2.1
FFI: Another fix for cdata equality comparisons.
Merge branch 'master' into v2.1
x64: Workaround for MSVC build issue.
Merge branch 'master' into v2.1
Merge branch 'v2.1' into v2.1-agentzh