lang/pypy: support cffi, fix and simplify.

• Mark as only for i386, amd64 and armv6 (JIT only supported on those archs)
• Move PyPy dir to pypy26 (for consistency with llvm, et al)
• Drop PYPY_ARCH (unused)
• Use shell to detect ${BUILD_WRKSRC}/Makefile [1]
• Enable CFFI for components that do not have external dependencies
• Update regression-test to align with upstreams procedures
• Complete changes for detecting cpu count via sysctl (upstreamed)
• Properly detect arm (upstreamed) [2]
• Update pkg-plist generation and regenerate

[1] When make evaluates the dependency for pre-build the variable
${BUILD_WRKSRC} is not fully defined (i.e. ${WRKSRC}) so it does not get
properly expanded causing make to never find the correct Makefile.

PR: 202159 [2]
Reviewed by: sbruno (prior version)