Makefile: Hardcoded installation paths should be replaced with environment variables #74
Description
Hard-coded values for paths (like /usr/local/...) in Makefile should be replaced with variables (like it was in 1.3.2) as it improves user experience and lightens the burden of package maintainers of different GNU/Linux distributions.
I myself just recently updated xfel to 1.3.2 in GNU Guix and used DESTDIR and PREFIX to set the right paths for installation. Now to update the package to the version 1.3.3 I must substitute hard-coded paths with proper ones by modifying the Makefile which is very inconvenient.
-avp