refactor(build): use dynamic cpu cores to compile code. (#265)

* Modify the default number of threads used for compilation to be the number of CPU logical cores instead of hardcode.

* Modify the default number of threads used for compilation on Linux and MAC platforms to be the number of CPU logical cores, rather than hardcode.

Author: WoodsCumming

build.sh

@@ -39,14 +39,18 @@ PrintParams() {
   echo ""
 }
 
+if test "$(uname)" = "Linux"; then
+  declare cpu_num=$(cat /proc/cpuinfo | grep "processor" | wc -l)
+elif test "$(uname)" = "Darwin" ; then
+  declare cpu_num=$(sysctl -n machdep.cpu.thread_count)
+fi
 declare need_build_jsoncpp=1
 declare need_build_libevent=1
 declare need_build_boost=1
 declare enable_asan=0
 declare enable_lsan=0
 declare verbose=1
 declare codecov=0
-declare cpu_num=4
 declare test=0
 
 pasres_arguments() {