tree-wide usage of %m specifier instead of strerror(errno)

Also for log_error() except where a specific error is specified

e.g. errno ? strerror(errno) : "Some user specified message"

src/core/automount.c

@@ -304,7 +304,7 @@ static int open_dev_autofs(Manager *m) {
 
         m->dev_autofs_fd = open("/dev/autofs", O_CLOEXEC|O_RDONLY);
         if (m->dev_autofs_fd < 0) {
-                log_error("Failed to open /dev/autofs: %s", strerror(errno));
+                log_error("Failed to open /dev/autofs: %m");
                 return -errno;
         }
 

src/core/main.c

@@ -131,7 +131,7 @@ _noreturn_ static void crash(int sig) {
 
                 pid = fork();
                 if (pid < 0)
-                        log_error("Caught <%s>, cannot fork for core dump: %s", signal_to_string(sig), strerror(errno));
+                        log_error("Caught <%s>, cannot fork for core dump: %m", signal_to_string(sig));
 
                 else if (pid == 0) {
                         struct rlimit rl = {};

src/core/manager.c

@@ -307,7 +307,7 @@ static int enable_special_signals(Manager *m) {
         } else {
                 /* Enable that we get SIGWINCH on kbrequest */
                 if (ioctl(fd, KDSIGACCEPT, SIGWINCH) < 0)
-                        log_warning("Failed to enable kbrequest handling: %s", strerror(errno));
+                        log_warning("Failed to enable kbrequest handling: %m");
         }
 
         return 0;

src/core/mount-setup.c

@@ -188,7 +188,7 @@ static int mount_one(const MountPoint *p, bool relabel) {
                   p->type,
                   p->flags,
                   p->options) < 0) {
-                log_full((p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG, "Failed to mount %s: %s", p->where, strerror(errno));
+                log_full((p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG, "Failed to mount %s: %m", p->where);
                 return (p->mode & MNT_FATAL) ? -errno : 0;
         }
 

src/core/service.c

@@ -3507,7 +3507,7 @@ static int service_enumerate(Manager *m) {
                         d = opendir(path);
                         if (!d) {
                                 if (errno != ENOENT)
-                                        log_warning("opendir(%s) failed: %s", path, strerror(errno));
+                                        log_warning("opendir(%s) failed: %m", path);
 
                                 continue;
                         }
@@ -3540,7 +3540,7 @@ static int service_enumerate(Manager *m) {
                                 if (access(fpath, X_OK) < 0) {
 
                                         if (errno != ENOENT)
-                                                log_warning("access() failed on %s: %s", fpath, strerror(errno));
+                                                log_warning("access() failed on %s: %m", fpath);
 
                                         continue;
                                 }