Remove unused plymouth_running() function

src/basic/meson.build

@@ -162,7 +162,6 @@ basic_sources = files('''
         parse-util.h
         path-util.c
         path-util.h
-        plymouth-util.c
         plymouth-util.h
         prioq.c
         prioq.h

src/basic/plymouth-util.c

@@ -1,9 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1+ */
-
-#include <unistd.h>
-
-#include "plymouth-util.h"
-
-bool plymouth_running(void) {
-        return access("/run/plymouth/pid", F_OK) >= 0;
-}

src/basic/plymouth-util.h

@@ -1,11 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 #pragma once
 
-#include <stdbool.h>
-
 #define PLYMOUTH_SOCKET {                                       \
                 .un.sun_family = AF_UNIX,                       \
                 .un.sun_path = "\0/org/freedesktop/plymouthd",  \
         }
-
-bool plymouth_running(void);