Fix OS X Lion (almost)
Fix OS X Lion (almost)

dlsym() in Lion now calls pthread_key_create() which breaks an
assumption coroutine.cc had made, causing infinite recursion. This
modifies the primordial pthread hooks to work under the new
constraints. This fix isn't complete as there is still segfaulting I
haven't quite tracked down yet.

metamatt/node-fibers,dut3062796s/node-fibers,d3m3vilurr/node-fibers,rydn/node-fibers,lzpfmh/node-fibers,dut3062796s/node-fibers,meteor/node-fibers,rydn/node-fibers,spookd/node-fibers,meteor/node-fibers,tempbottle/node-fibers,metamatt/node-fibers,tempbottle/node-fibers,xolvio/node-fibers,laverdet/node-fibers,Sanjo/node-fibers,pjump/node-fibers,lzpfmh/node-fibers,Icenium/node-fibers,palsmadal/node-fibers,cgvarela/node-fibers,Sanjo/node-fibers,spookd/node-fibers,tempbottle/node-fibers,tempbottle/node-fibers,pjump/node-fibers,dut3062796s/node-fibers,laverdet/node-fibers,d3m3vilurr/node-fibers,meteor/node-fibers,laverdet/node-fibers,palsmadal/node-fibers,xolvio/node-fibers,cgvarela/node-fibers,pjump/node-fibers,palsmadal/node-fibers,Sanjo/node-fibers,rydn/node-fibers,dut3062796s/node-fibers,pjump/node-fibers,Icenium/node-fibers,spookd/node-fibers,d3m3vilurr/node-fibers,cgvarela/node-fibers,lzpfmh/node-fibers,lzpfmh/node-fibers,Icenium/node-fibers,meteor/node-fibers,xolvio/node-fibers,palsmadal/node-fibers,d3m3vilurr/node-fibers,laverdet/node-fibers,metamatt/node-fibers,Sanjo/node-fibers,cgvarela/node-fibers,spookd/node-fibers,rydn/node-fibers,Icenium/node-fibers,xolvio/node-fibers,metamatt/node-fibers