The year is now included in the copyright string used in the makefiles
and so they need to be regenerated every time the year changes (which
happens surprisingly frequently).
It would be better to define a single variable with the year number to
avoid having to do this in the future.
Simply remove the not existent any longer shared-ld-sh from clean
targets in all makefile.
This should have been done in e663d9af2b (Stop using shared-ld wrapper
script under Mac, 2021-07-06).
