get correct number of cores info in MacOSX

no /proc file system in MacOSX. use sysctl to return correct number of
cores to speed up building.

Change-Id: Ic813521c5867fd3c5ac1f565894dcb89aa1a3579

build.sh

@@ -25,7 +25,11 @@ txtrst=$(tput sgr0)             # Reset
 
 # Local defaults, can be overriden by environment
 : ${PREFS_FROM_SOURCE:="false"}
+if [ `uname -s` == "Darwin" ]; then
+: ${THREADS:="$(sysctl -n machdep.cpu.core_count)"}
+else
 : ${THREADS:="$(cat /proc/cpuinfo | grep "^processor" | wc -l)"}
+fi
 
 # If there is more than one jdk installed, use latest 6.x
 if [ "`update-alternatives --list javac | wc -l`" -gt 1 ]; then