meson: Rely on libfprint dependency to get root_include

No need to redefine it in all our tools

examples/meson.build

@@ -4,14 +4,10 @@ foreach example: examples
     executable(example,
         [ example + '.c', 'storage.c', 'utilities.c' ],
         dependencies: [ libfprint_dep, glib_dep ],
-        include_directories: [
-            root_inc,
-        ])
+    )
 endforeach
 
 executable('cpp-test',
     'cpp-test.cpp',
     dependencies: libfprint_dep,
-    include_directories: [
-        root_inc,
-    ])
+)