* Fix varmod-localtime test by setting TZ to an absolute path to the
appropriate file in TZDIR. This avoids having an extra patch for musl
which doesn't support TZDIR at all.
* Move tests into checkPhase by applying patch from alpine
* Fix build with musl by disabling deptgt-delete_on_error test (which I
haven't debugged myself, just copied this from alpine) and fixing a
test which fails due to differing output from strerror(3) between musl
and glibc. Also we need to add a shebang to install-sh, otherwise it
won't be executed in pkgsMusl.
