Merge pull request #1031 from scop/getconf

Get number of processors using getconf over cpuinfo grep

plugins/python-build/bin/python-build

@@ -155,7 +155,8 @@ num_cpu_cores() {
     num="$(sysctl -n hw.ncpu 2>/dev/null || true)"
     ;;
   * )
-    num="$(grep ^processor /proc/cpuinfo 2>/dev/null | wc -l | xargs)"
+    num="$({ getconf _NPROCESSORS_ONLN ||
+             grep -c ^processor /proc/cpuinfo; } 2>/dev/null)"
     num="${num#0}"
     ;;
   esac