[jhc] darcs patch: Support concurrent (and 2 more)

3 patches for repository http://repetae.net/repos/jhc: Tue Nov 5 17:40:09 JST 2013 kiwamu@debian.or.jp * Support concurrent The long patch to support concurrent. The concurrent mean concurrent GC, forkOS, running some context same time. The patch chooses some thread type, -fnothread or -fpthread or -fcustomthread. Default is -fpthread. If choose -fcustomthread, you should implement thread backend on application side. Tue Nov 5 17:55:08 JST 2013 kiwamu@debian.or.jp * Pass rts/test with concurrent Tue Nov 5 17:56:39 JST 2013 kiwamu@debian.or.jp * Selftest with Test.Framework.TH