binfmt-util: rename binfmt_mounted() -> binfmt_mounted_and_writable()

As it does not only check if binfmt_misc is mounted, but also check if
it is writable.

src/shared/binfmt-util.c

@@ -11,7 +11,7 @@
 #include "missing_magic.h"
 #include "stat-util.h"
 
-int binfmt_mounted(void) {
+int binfmt_mounted_and_writable(void) {
         _cleanup_close_ int fd = -EBADF;
         int r;
 
@@ -43,7 +43,7 @@ int disable_binfmt(void) {
          * We are a bit careful here, since binfmt_misc might still be an autofs which we don't want to
          * trigger. */
 
-        r = binfmt_mounted();
+        r = binfmt_mounted_and_writable();
         if (r < 0)
                 return log_warning_errno(r, "Failed to determine whether binfmt_misc is mounted: %m");
         if (r == 0) {

src/shared/binfmt-util.h

@@ -1,5 +1,5 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 #pragma once
 
-int binfmt_mounted(void);
+int binfmt_mounted_and_writable(void);
 int disable_binfmt(void);