build/meson: rename "nm_core_dep" to "libnm_core_dep"

The library is called "libnm_core". So the dependency should be called
"libnm_core_dep", like in all other cases.

(cherry picked from commit c27ad37c27)

examples/C/glib/meson.build

@@ -14,6 +14,6 @@ foreach example: examples
     example[0],
     [example[0] + '.c'] + example[1],
     include_directories: example[2],
-    dependencies: [nm_core_dep] + example[3],
+    dependencies: [libnm_core_dep] + example[3],
   )
 endforeach