Remove pool allocator for coroutine stacks
Remove pool allocator for coroutine stacks

There is little performance benefit here, if any. It also may be
harmful, since the chunks of memory allocated are very large anyway.
Since this is GNU-specific and complicates compilation on Windows, away
it goes.

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