thread-utils.c: detect CPU count on older BSD-like systems
Not all systems support using sysconf to detect the number
of available CPU cores. Older BSD and BSD-derived systems
only provide the information via the sysctl function.
If HAVE_BSD_SYSCTL is defined attempt to retrieve the number
of available CPU cores using the sysctl function.
If HAVE_BSD_SYSCTL is not defined or the sysctl function
fails, we still attempt to get the information via sysconf.
Signed-off-by: Kyle J. McKay <mackyle@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>