The -N option / drv_N type only makes sense when we are compiling
guestfish, and just serves to complicate non-guestfish code.

Because the shell script was missing a space, the final output test
was failing, although for some reason this didn't cause the whole test
to fail.

Fixing the missing space also revealed a bug in the test output, which
is also fixed.

This test was present in git, but not included in the tarball,
nor in the tests that guestfish actually runs.

This fixes commit 17182af3a6de8e3e94e0a914416c54f09bb74007.

'make extra-tests' was a monolithic set of tests that did all sorts of
things: valgrind, tests over local guests, tests with upstream qemu,
tests with upstream libvirt, tests with the appliance attach method.

This made it hard to perform individual tests, eg. just valgrind
testing.  It was also hard to maintain because the tests were not
located in the same directories as the programs and sometimes
duplicated tests that were run elsewhere.

This commit splits up 'make extra-tests' into 5 separate targets:

 make check-valgrind              # run a subset of tests under valgrind
 make check-valgrind-local-guests # test under valgrind with local guests
 make check-with-appliance        # test with attach-method == appliance
 make check-with-upstream-qemu    # test with an alternate/upstream qemu
 make check-with-upstream-libvirt # test with an alternate/upstream libvirt

(You can also still run 'make extra-tests' which is now simply
a rule that runs the above 5 targets in order).

This replaces everything that was in the tests/extra directory,
so that has now gone.

This is a shorter and more convenient way to disable errors
temporarily across calls.

This fixes commit 1efed122c07792f4c66a4083159cfacfb1893212.

New APIs: set-tmpdir, get-tmpdir, set-cachedir, get-cachedir.

The current code has evolved over time and has a number of problems:

(a) A single environment variable ($TMPDIR) controls the
location of several directories.

(b) It's hard for the library user to predict which directory
libguestfs will use, unless the user simulates the same internal steps
that libguestfs performs.

This commit fixes these issues.

(a) Now three environment variables control the location of all small
temporary files, and the appliance cache:

  For temporary files: $LIBGUESTFS_TMPDIR or $TMPDIR or /tmp.

  For the appliance cache: $LIBGUESTFS_CACHEDIR or $TMPDIR or /var/tmp.

The user can also set these directories explicitly through API calls
(guestfs_set_tmpdir and guestfs_set_cachedir).

(b) The user can also retrieve the actual directories that libguestfs
will use, by calling guestfs_get_tmpdir and guestfs_get_cachedir.
These functions are also used internally.

This commit also:

 - reworks the internal tmpdir code

 - removes the internal (undocumented) guestfs_tmpdir call (replacing
   it with calls to the documented guestfs_get_tmpdir API instead)

 - changes the ./run script to set LIBGUESTFS_TMPDIR and
   LIBGUESTFS_CACHEDIR

 - adds a test

 - fixes a few places like libguestfs-make-fixed-appliance which
   depended on $TMPDIR