Plugins also may use nmtst_*() functions (when built with --with-more-asserts)
or c_list_*(). Whitelist them too.

The functionality of the ibft settings plugin is now handled by
nm-initrd-generator. There is no need for it anymore, drop it.

Note that ibft called iscsiadm, which requires CAP_SYS_ADMIN to work
([1]). We really want to drop this capability, so the current solution
of a settings plugin (as it is implemented) is wrong. The solution
instead is nm-initrd-generator.

Also, on Fedora the ibft was disabled and probably on most other
distributions as well. This was only used on RHEL.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1371201#c7

When building with meson -Dppp=false, the following message is printed
during build:

  [623/671] Generating NetworkManager.ver with a custom command. find: ‘./src/ppp/’: No such file or directory

The message is harmless. Hide it.

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/issues/43

The script didn't include all the symbols needed by plugins because
libNetworkManager.a, as built by meson, doesn't include symbols from
other static libraries that are linked in. Since we used
libNetworkManager.a to know which symbols are potentiall available
from NM, the result was an incomplete list.

Unfortunately, the only way to include the whole static library is to
create a dependency object and use 'link_whole', but this is only
available in meson >= 0.46. Since 'link_whole' is available for
executables in meson >= 0.40, create a fake executable and use that to
enumerate symbols.

Also add tests to check that plugins can be loaded correctly.

Fixes: dfa2a2b40c866bf7a5484b72639464c31b80e7da

(cherry picked from commit 9b4bc0824c1d8925f1ecfa4856757d322f030427)

NetworkManager.ver needs to whitelist symbols needed by device,
settings, and ppp plugin. Fix the generator script to also allow
using c_siphash_*() symbols. These are needed by nm_hash_*().

Without this, wifi device plugin is broken.

Fixes: ccf36ff4cea6eb6a7ecd872563dfbd3a00f8cfdf

Even Gentoo disables this plugin since before 0.9.8 release
of NetworkManager. Time to say goodbye.

If somebody happens to show up to maintain it, we may resurrect it
later.

If "$distro_plugins=ifnet" was set, configure.ac would use that
to autodetect --with-hostname-persist=gentoo. Replace that autodetect
part by checking for /etc/gentoo-release file.

On ppc archtecture the "nm_bt_vtable_network_server" symbol in the small
objects section instead of .bss, represencted by a "S" letter. Also
include "G" which is an equivalent thing for initialized data. We don't
seem to have such objects at the moment, but when we do it could result
in a nasty surprise.

When building with -flto, we need to use linker plugins.
In case of binutils' nm, it means to prefer gcc-nm if
available.

Like for ranlib and ar, prefer gcc-nm.

- replace AC_PATH_TOOL() by AC_CHECK_TOOLS(). That is consistent
  with what we do for ar,ranlib and suggested on bgo#783311.
- instead of using the variable $BINUTILS_NM, replace it by
  $NM, which is more common according to bgo#783311.
- Keep recognizing $BINUTILS_NM environment, which was introduced
  by commit 8bc88bcc7c. This is purely to keep previous build
  scripts working. Originally I named it "$BINUTILS_NM" because
  using $NM in NetworkManager seemed confusing. But well...

https://bugs.gentoo.org/show_bug.cgi?id=620052
https://bugzilla.gnome.org/show_bug.cgi?id=782525
https://bugzilla.gnome.org/show_bug.cgi?id=783311