Make fopen_temporary and fopen_temporary_label unlocked

This is partially a refactoring, but also makes many more places use
unlocked operations implicitly, i.e. all users of fopen_temporary().
AFAICT, the uses are always for short-lived files which are not shared
externally, and are just used within the same context. Locking is not
necessary.

src/shared/generator.c

@@ -1,7 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
 #include <errno.h>
-#include <stdio_ext.h>
 #include <unistd.h>
 
 #include "alloc-util.h"
@@ -30,23 +29,22 @@ int generator_open_unit_file(
 
         const char *unit;
         FILE *f;
+        int r;
 
         unit = strjoina(dest, "/", name);
 
-        f = fopen(unit, "wxe");
-        if (!f) {
-                if (source && errno == EEXIST)
-                        return log_error_errno(errno,
+        r = fopen_unlocked(unit, "wxe", &f);
+        if (r < 0) {
+                if (source && r == -EEXIST)
+                        return log_error_errno(r,
                                                "Failed to create unit file %s, as it already exists. Duplicate entry in %s?",
                                                unit, source);
                 else
-                        return log_error_errno(errno,
+                        return log_error_errno(r,
                                                "Failed to create unit file %s: %m",
                                                unit);
         }
 
-        (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
-
         fprintf(f,
                 "# Automatically generated by %s\n\n",
                 program_invocation_short_name);

src/shared/mount-util.c

@@ -1,7 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
 #include <errno.h>
-#include <stdio_ext.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/mount.h>