libkmod: turn into dlopen() dependency

As it turns out libkmod has quite a bunch of deps, including various
compressing libs and similar. By turning this into a dlopen()
dependency, we can make our depchain during install time quite a bit
smaller. In particular as inside of containers kmod doesn't help anyway
as CAP_SYS_MODULE is not available anyway.

While we are at it, also share the code that sets up logging/kmod
context.

After:

$ lddtree ./build/systemd
systemd => ./build/systemd (interpreter => /lib64/ld-linux-x86-64.so.2)
    libsystemd-core-255.so => ./build/src/core/libsystemd-core-255.so
        libaudit.so.1 => /lib64/libaudit.so.1
            libcap-ng.so.0 => /lib64/libcap-ng.so.0
                ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2
        libm.so.6 => /lib64/libm.so.6
        libmount.so.1 => /lib64/libmount.so.1
            libblkid.so.1 => /lib64/libblkid.so.1
        libseccomp.so.2 => /lib64/libseccomp.so.2
        libselinux.so.1 => /lib64/libselinux.so.1
            libpcre2-8.so.0 => /lib64/libpcre2-8.so.0
    libsystemd-shared-255.so => /home/lennart/projects/systemd/build/src/shared/libsystemd-shared-255.so
        libacl.so.1 => /lib64/libacl.so.1
            libattr.so.1 => /lib64/libattr.so.1
        libcap.so.2 => /lib64/libcap.so.2
        libcrypt.so.2 => /lib64/libcrypt.so.2
        libgcrypt.so.20 => /lib64/libgcrypt.so.20
            libgpg-error.so.0 => /lib64/libgpg-error.so.0
        liblz4.so.1 => /lib64/liblz4.so.1
        libcrypto.so.3 => /lib64/libcrypto.so.3
            libz.so.1 => /lib64/libz.so.1
        libpam.so.0 => /lib64/libpam.so.0
            libeconf.so.0 => /lib64/libeconf.so.0
        liblzma.so.5 => /lib64/liblzma.so.5
        libzstd.so.1 => /lib64/libzstd.so.1
    libc.so.6 => /lib64/libc.so.6

Before:

$ lddtree ./build/systemd
systemd => ./build/systemd (interpreter => /lib64/ld-linux-x86-64.so.2)
    libsystemd-core-255.so => ./build/src/core/libsystemd-core-255.so
        libaudit.so.1 => /lib64/libaudit.so.1
            libcap-ng.so.0 => /lib64/libcap-ng.so.0
                ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2
        libkmod.so.2 => /lib64/libkmod.so.2
            libzstd.so.1 => /lib64/libzstd.so.1
            liblzma.so.5 => /lib64/liblzma.so.5
            libz.so.1 => /lib64/libz.so.1
            libcrypto.so.3 => /lib64/libcrypto.so.3
            libgcc_s.so.1 => /lib64/libgcc_s.so.1
        libm.so.6 => /lib64/libm.so.6
        libmount.so.1 => /lib64/libmount.so.1
            libblkid.so.1 => /lib64/libblkid.so.1
        libseccomp.so.2 => /lib64/libseccomp.so.2
        libselinux.so.1 => /lib64/libselinux.so.1
            libpcre2-8.so.0 => /lib64/libpcre2-8.so.0
    libsystemd-shared-255.so => /home/lennart/projects/systemd/build/src/shared/libsystemd-shared-255.so
        libacl.so.1 => /lib64/libacl.so.1
            libattr.so.1 => /lib64/libattr.so.1
        libcap.so.2 => /lib64/libcap.so.2
        libcrypt.so.2 => /lib64/libcrypt.so.2
        libgcrypt.so.20 => /lib64/libgcrypt.so.20
            libgpg-error.so.0 => /lib64/libgpg-error.so.0
        liblz4.so.1 => /lib64/liblz4.so.1
        libpam.so.0 => /lib64/libpam.so.0
            libeconf.so.0 => /lib64/libeconf.so.0
    libc.so.6 => /lib64/libc.so.6

1 files changed, 1 insertions, 1 deletions

diff --git a/test/test-functions b/test/test-functions
index 5d63a41d80..a09092a5b0 100644
--- a/test/test-functions
+++ b/test/test-functions
@@ -1555,7 +1555,7 @@ install_missing_libraries() {
     local lib path
     # A number of dependencies is now optional via dlopen, so the install
     # script will not pick them up, since it looks at linkage.
-    for lib in libcryptsetup libidn libidn2 pwquality libqrencode tss2-esys tss2-rc tss2-mu tss2-tcti-device libfido2 libbpf libelf libdw xkbcommon p11-kit-1 libarchive libgcrypt; do
+    for lib in libcryptsetup libidn libidn2 pwquality libqrencode tss2-esys tss2-rc tss2-mu tss2-tcti-device libfido2 libbpf libelf libdw xkbcommon p11-kit-1 libarchive libgcrypt libkmod; do
         ddebug "Searching for $lib via pkg-config"
         if pkg-config --exists "$lib"; then
                 path="$(pkg-config --variable=libdir "$lib")"