tst-vfs: don't rely on some random Java file

tst-vfs.cc currently stat()s the file
	/usr/lib/jvm/jre/lib/amd64/headless/libmawt.so
And dies if it doesn't exist.

Since Java is now optional in our images, it's not a good idea to check
for such a file, which might not exist (e.g., "make image=tests check"
will fail). This patch changes it to check a filename that is certain to
exist, like namely the test itself - /tests/tst-vfs.so.

If we wanted to have a pathname with more components, the test should
be rewritten to create this pathname, say /a/a/a/a/a/a/a/a/a/a, and then
test stat on that newly created file. It cannot rely on such a file to
pre-exist.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
modules: Move more files to modules/{java,mgmt}/usr.manifest

After the creation of the "java" and "mgmt" modules, we still left with a
bunch of files in the main usr.manifest.skel which really belong in the
modules/{java,mgmt}/usr.manifest.

This patch moves various shared libraries and fonts which Java needs
(the fonts are needed for AWT, including headless AWT), as well as
various JNI shared objects and our java.so and runjava.jar, into the
"java" module, and moves a couple of tools (ifconfig, lsroute) and
configuration file (/etc/inputrc used by the management module into
the "mgmt" module.

This reduces small OSv appliances, like "make image=memcached", which
don't need Java, by 13 MB. We are still left with 69 MB, most of which
are tests, so the next item on the todo is to move the tests into a
"test" module.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Makefile: get rid of "make external"

Our need for "make external" was plagued with problems. First and formost,
it was annoying - people need to be told to run "make all external" instead
of just "make". And as a Vlad recently discovered, it strangely relied on a
debug-mode build to have happened, and also "make clean" doesn't undo what
"make external" did.

"make external" had a glorious past, but today all that was left of it
is 3 measly tests which we compile from external/glibc-testsuite: malloc,
getcwd and clock. These tiny tests - 3 out of 796 tests (!!) in the full
glibc test suite - aren't really important enough to cause all this
"make external" mess. So this patch removes them, and the need for a
"make external".

If we'll ever want to bring back these tests, I think we need to delete the
partial external/glibc-testsuite directory, and bring the *full* glibc
test suite of 796 tests, into a separate module. The glibc test suite can be
downloaded together with the glibc source code - they are all files named
tst-*.c in the glibc source tree.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>