Fixes <https://issues.guix.gnu.org/50830>.
Reported by podiki on #guix.
Previously, glibc 2.33 would look for
/gnu/store/...-glibc-2.33/etc/localtime instead of /etc/localtime.
* gnu/packages/base.scm (glibc)[arguments]: Remove #:make-flags.
[phases]: In 'pre-configure', modify 'inet/Makefile' instead of
'sunrpc/Makefile' since this is where these bits are in 2.33.
(glibc-2.31)[arguments]: Add 'set-etc-rpc-installation-directory'
phase.
(glibc-2.30): Inherit from GLIBC-2.31.
* gnu/tests/base.scm (run-basic-test)["libc honors /etc/localtime"]: New
test.
Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>