Fix a race condition in oxt::syscalls::fork() that could cause an infinite loop.
Fix a race condition in oxt::syscalls::fork() that could cause an infinite loop.

bf4/passenger,clemensg/passenger,bf4/passenger,phusion/passenger,bf4/passenger,phusion/passenger,phusion/passenger,jawj/passenger,kewaunited/passenger,clemensg/passenger,antek-drzewiecki/passenger,phusion/passenger,antek-drzewiecki/passenger,clemensg/passenger,cgvarela/passenger,clemensg/passenger,antek-drzewiecki/passenger,cgvarela/passenger,antek-drzewiecki/passenger,jawj/passenger,phusion/passenger,cgvarela/passenger,cgvarela/passenger,antek-drzewiecki/passenger,kewaunited/passenger,clemensg/passenger,kewaunited/passenger,jawj/passenger,kewaunited/passenger,phusion/passenger,cgvarela/passenger,kewaunited/passenger,phusion/passenger,bf4/passenger,cgvarela/passenger,cgvarela/passenger,antek-drzewiecki/passenger,jawj/passenger,bf4/passenger,bf4/passenger,antek-drzewiecki/passenger,phusion/passenger,clemensg/passenger,jawj/passenger,bf4/passenger,antek-drzewiecki/passenger,kewaunited/passenger,clemensg/passenger,kewaunited/passenger,cgvarela/passenger,clemensg/passenger,jawj/passenger,kewaunited/passenger,jawj/passenger