DragonFly - Change PTHREAD_STACK_MIN from 1 to 16k
DragonFly - Change PTHREAD_STACK_MIN from 1 to 16k

This is probably related to cargo failing on DragonFly when running with
multiple jobs.

The minimum pthread stack size has been increase as shown here [1],
which was needed to fix nodejs.

[1]: http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/592912cde1dc358bf080ae9aff3eca491688f47c

cactorium/libc,rust-lang/libc,rust-lang-nursery/libc,rust-lang-nursery/libc,rust-lang/libc,mneumann/libc,cactorium/libc,mneumann/libc,rust-lang/libc,cactorium/libc,mneumann/libc,rust-lang-nursery/libc