meson: do not build module-util.c when libkmod is not found

Follow-up for 3cb9b42af3 (#9516).

Fixes oss-fuzz-9532.

src/shared/meson.build

@@ -64,7 +64,6 @@ shared_sources = files('''
         machine-pool.c
         machine-pool.h
         module-util.h
-        module-util.c
         nsflags.c
         nsflags.h
         output-mode.c
@@ -125,6 +124,10 @@ if conf.get('HAVE_LIBIPTC') == 1
         shared_sources += files('firewall-util.c')
 endif
 
+if conf.get('HAVE_KMOD') == 1
+        shared_sources += files('module-util.c')
+endif
+
 libshared_name = 'systemd-shared-@0@'.format(meson.project_version())
 
 libshared_deps = [threads,