Cleaning means to remove build artifacts from the directory @builddir@ (= SAGE_ROOT).
But these targets uninstall packages from @prefix@=$SAGE_LOCAL.

Hence we rename SPKG-clean targets to SPKG-uninstall (but keep SPKG-clean as an alias.) This also unifies the targets between normal and script packages (the latter used -uninstall already).

We also add implicit rules that allow users to uninstall packages that no longer exist in the source tree. This is preparation for #34203. To test this, switch to the branch of #33530 and build one of the packages added, for example make fastjsonschema. Switch back to current develop and try to remove it (does not work). Switch to the branch here and run make fastjsonschema-uninstall (works).

Related:

• "make distclean" should not run "./configure" #29310 - introduced make doc-uninstall
• "make doc-clean" should remove inventory, doctrees #33705 make doc-clean should remove inventory, doctrees
• Install script and pip packages via sage-spkg #29386 Install script packages via sage-spkg
• Remove ./configure --enable-SPKG options for pip packages (for which this is not implemented) #29626 ./configure --enable-SPKG does not work for optional pip packages
• pip-installable packages sagemath-doc-src, sagemath-doc-inventory, sagemath-doc-html, sagemath-doc-pdf #29868 pip-installable packages sage-doc-html, sage-doc-pdf

CC: @dimpase @embray @jhpalmieri @seblabbe @orlitzky @haraldschilly

Component: build

Author: John Palmieri, Matthias Koeppe

Branch/Commit: 72695aa

Reviewer: Matthias Koeppe, John Palmieri

Issue created by migration from https://trac.sagemath.org/ticket/29097