testsuite: add test for kcmdline params with no value

Use "modprobe -c" to dump the configuration. Since we configure our
rootfs to have only a /proc/cmdline file, this should dump the knowledge
we have from its parsed content.

Test if <module>.option, without any value is correctly parsed, as fixed
in commit 493dc65 ("libkmod: Fix getting param with no value from kcmdline")
testsuite: give a more suitable description to test

We are not only checking if those options are correctly parsed from
kcmdline, but if in fact they are being passed to the final
(f)init_module call. This is why we use 'modprobe --show-depends'
instead of the simpler 'modprobe -c'.
testsuite: add test to ignore unrelated strings in kcmdline

Strings unrelated to modules and modprobe should be ignored and not
appear in the output of "modprobe -c".

This adds a test for the fix provided in aa87854 ("libkmod-config: Only
match dot before '=' in /proc/cmdline").
testsuite: add test for '.' correctly parsed in param's value

In kcmdline it's possible to have a dot in the param's value. The
support for this was added in 66f3228 ("libkmod: Add support for '.' in
module parameter on kcmdline") and is needed to correctly support some
modules that depend on it.

This test was added in order to make sure the commit  aa87854
("libkmod-config: Only match dot before '=' in /proc/cmdline") didn't
break it. Although that commit  message says it's allowing to match a
dot before '=' it's actually enforcing the first part of the string to
be always in the format "<module-name>.param". Dots after '=' are still
correctly allowed.
build-sys: add small redirecting Makefiles

These redirecting makefiles simplifies compiling from some editors and
when CWD is not the root of the source tree. This is similar to what was
introduced in systemd in 340d89e ("build-sys: add small redirecting
Makefiles to simplify compilation from within emacs")
build-sys: Do not require xsltproc for installation of man pages

Same reason as found in this commit to systemd:

	commit 4ca39b280fce3c60d2fdecbd478fd9bf7f9d3e64
	Author: Mike Gilbert <floppym@gentoo.org>
	Date:   Sun Feb 23 11:21:13 2014 -0500

	    configure: Do not require xsltproc for installation of man pages

	    The release tarballs ship with pre-generated man pages, so we do not
	    need xsltproc for a typical end-user build.

	    Developers will probably have xsltproc anyway, but if not they will now
	    encounter a build-time failure instead of an error in configure.
man: clarify the support to modules.dep file
man: use systemd as example instead of udev

Nowadays udev doesn't create nodes in /dev anymore. This role is rather
taken by systemd-tmpfiles on early boot so reference it generically as
systemd.
testsuite: Fix uname() during glibc startup

In a specific configuration (chroot with the linux32 personality), the
modprobe_install_cmd_loop test failed, because the bash process handling
the install command segfaulted. The backtrace showed a uname() call
during libpthread initialization, at which point the environ pointer
hadn't been initialized yet:

	Program terminated with signal SIGSEGV, Segmentation fault.
	#0  0x080c1591 in getenv (name=<optimized out>,
	    name@entry=0xf775f850 "TESTSUITE_UNAME_R") at getenv.c:81
	81	      for (i = 0, len = strlen (name); environ[i]; i++)
	(gdb) bt
	#0  0x080c1591 in getenv (name=<optimized out>,
	    name@entry=0xf775f850 "TESTSUITE_UNAME_R") at getenv.c:81
	#1  0xf775f754 in uname (u=u@entry=0xff946350) at testsuite/uname.c:32
	#2  0xf74ffc6c in is_smp_system ()
	    at ../nptl/sysdeps/unix/sysv/linux/i386/smp.h:39
	#3  __pthread_initialize_minimal_internal () at nptl-init.c:460
	#4  0xf74fe32c in _init () at ../sysdeps/i386/crti.S:74
	#5  0x00000000 in ?? ()
	(gdb) p environ
	$1 = (char **) 0x0

I don't know why it only happend in the chroot, but glibc can call its
own functions and impose any restrictions before main() is started, so
we have to adapt.

Also, do not return error if there is an environment, but the
environment variable is not found. If uname() is called by kmod, then
the respective test will simply fail later. If it's something else
calling uname(), then we do not want to disturb the program.
libkmod-elf: Fix check by class in get_modversions()

Commit 51c409b ("Cache the offset of crc") unintentinally changed the
comparison "if (elf->class & KMOD_ELF_32)" to
"if (elf->class == KMOD_ELF_32)".

This has been reported by Serge Voilokov <serge0x76@gmail.com>:

	On Raspberry PI elf->class equals KMOD_ELF_32|KMOD_ELF_LSB so
	valid condition should be (elf->class & KMOD_ELF_32) instead of
	(elf->class == KMOD_ELF_32).

This fixes "modprobe --dump-modversions" failing on 32b systems.