Drop obsolete patches:
- patch-Makefile: obsoleted by changing into t/ within do-test
- patch-perl_Makefile_PL: removed upstream
- patch-t_t0000-basic_sh, patch-t_t9200-git-cvsexportcommit_sh: succeed
- patch-t_test-lib_sh: "70ec6bd63 Stop using sum(1)" (14.08.2017)
While here, use Python 3 and replace `cd && make' with `make -C'.
OK benoit danj
e9a58eab09