* build-aux/test-env.in: Pass ‘--disable-chroot’ only when unprivileged
user namespace support is lacking and warn in that case.
* tests/store.scm ("build-things, check mode"): Use ‘gettimeofday’
rather than a shared file as a source of entropy.
("symlink is symlink")
("isolated environment", "inputs are read-only")
("inputs cannot be remounted read-write")
("build root cannot be made world-readable")
("/tmp, store, and /dev/{null,full} are writable")
("network is unreachable"): New tests.
* tests/processes.scm ("client + lock"): Skip when
‘unprivileged-user-namespace-supported?’ returns true.

Change-Id: I3b3c3ebdf6db5fd36ee70251d07b893c17ca1b84

* tests/processes.scm (binfmt-misc?): New procedure,
(test-assert*): new procedure that skips the test if binfmt-misc? returns

* guix/scripts/processes.scm, tests/processes.scm: New files.
* Makefile.am (MODULES): Add the former.
(SCM_TESTS): Add the latter.
* po/guix/POTFILES.in: Add guix/scripts/processes.scm.
* doc/guix.texi (Invoking guix processes): New node.
(Invoking guix-daemon): Reference it.