fixup count of physical cores in discourse-setup (#739)

See also PR #702 for branch master

discourse-setup

@@ -257,7 +257,7 @@ scale_ram_and_cpu() {
     avail_cores=`sysctl hw.ncpu | awk '/hw.ncpu:/ {print $2}'`
   else
     avail_gb=$(check_linux_memory)
-    avail_cores=$((`awk '/cpu cores/ {print $4;exit}' /proc/cpuinfo`*`sort /proc/cpuinfo | uniq | grep -c "physical id"`))
+    avail_cores=`lscpu --parse=core | egrep -v ^# | sort -u | wc -l`
   fi
   echo "Found ${avail_gb}GB of memory and $avail_cores physical CPU cores"