Bug #64163 for ExtUtils-MakeMaker: clean_subdirs infinite loop if subdir already gone

In ExtUtils::MakeMaker 6.57_06 on recent i386 debian 5.10.1, the clean_subdirs rule goes into an infinite loop if the subdir it's trying to clean is already gone. The rule comes out for me as something like clean_subdirs : $(ABSPERLRUN) -e 'chdir '\''Foo-123'\''; system '\''$(MAKE) clean'\'' if -f '\''$(FIRST_MAKEFILE)'\'';' -- I think if the chdir fails because there's no such Foo-123 subdir any more, then it remains in the toplevel dir, where there's still a Makefile, so a further "make clean" is initiated, which repeats clean_subdirs, etc. I struck this when I'd accidentally untarred another dist in a working dir. On manually removing that offending dir a "make clean" then went into this loop. I suppose if a subdir is already gone then that would count as success for cleaning it. But perhaps other errors from chdir, like no perms to visit the dir any more, or some system I/O error, might make the rule fail, in the interests of not letting badness go undetected.