Credit goes to so many sources and inspirations:
* trava90 of the Pale Moon project
* firefox-61.0.2-3.fc28.src.rpm
* https://build.opensuse.org/package/view_file/network/palemoon/palemoon.spec?expand=1
* instructions for compiling on centos 6 and 7 http://developer.palemoon.org/Developer_Guide:Build_Instructions/Pale_Moon/Linux#head:CentOS_6