configure.ac: rework/fix the NEEDS_RESOLV and NEEDS_LIBGEN tests
The "action" parameters for these two tests were supplied incorrectly for the way the tests were implemented. The tests check whether a program which calls hstrerror() or basename() successfully links when -lresolv or -lgen are used, respectively. A successful linking would result in NEEDS_RESOLV or NEEDS_LIBGEN being unset, and failure would result in setting the respective variable.
Aside from that issue, the tests did not handle the case where neither library was necessary for accessing the functions in question. So solve both of these issues by re-working the two tests so that their form is like the NEEDS_SOCKET test which attempts to link with just the c library, and if it fails then assumes that the additional library is necessary and sets the appropriate variable.
Also an entry in the config.mak.in file is necessary for the NEEDS_LIBGEN variable to appear in the config.mak.autogen file with the value assigned by the configure script. Without it, the generated shell script would contain a snippet like this:
for ac_lib in ; do ...
which is incorrect.
Signed-off-by: Brandon Casey <email@example.com> Signed-off-by: Junio C Hamano <firstname.lastname@example.org>