ruby 2.0.0-p353

Also switch to downloading via CDN
swi-prolog: install to libexec and wrap

swi-prolog does not like being called through a symlink, so don't

Fixes #24323.
qwt: enable build with libc++ on Mavericks

Closes #24587.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>