"""
Spec says that on success pthread_create returns 0. It does not say
that an error code will be < 0. Linux glibc2 pthread_create() returns
ENOMEM (12) when one exceed process limits. (It looks like it should
return EAGAIN, but that's another story.)

For reference, see:
http://www.opengroup.org/onlinepubs/7908799/xsh/pthread_create.html
"""

[I have a feeling that similar bugs were fixed before; perhaps someone
could check that all error checks no check for != 0?]