Makefile中添加获取编译的任务数

本内容转自：https://blog.csdn.net/robertsong2004/article/details/39012455

#
# Do a parallel build with multiple jobs, based on the number of CPUs online
# in this system: 'make -j8' on a 8-CPU system, etc.
#
# (To override it, run 'make JOBS=1' and similar.)
#
ifeq ($(JOBS),)
  JOBS := $(shell grep -c ^processor /proc/cpuinfo 2>/dev/null)
  ifeq ($(JOBS),)
    JOBS := 1
  endif
endif