tree-wide: include sys/stat.h where necessary

These source files uses symbols provided by sys/stat.h, e.g. struct stat,
S_IFREG, S_IFBLK, and so on. Let's explicitly include sys/stat.h where
necessary.

Glibc's fcntl.h includes bits/stat.h, which provides these symbols, so
these symbols can be used without explicitly including sys/stat.h. But,
based on the discussion in #37922, we should explicitly include relevant
headers, and should not rely on the indirect inclusion.

Similar to 4f18ff2e29, but for sys/stat.h.

src/basic/env-file.c

@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <sys/stat.h>
 #include <unistd.h>
 
 #include "alloc-util.h"

src/bootctl/bootctl.c

@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
 #include <getopt.h>
+#include <sys/stat.h>
 
 #include "sd-varlink.h"
 

src/libsystemd/sd-journal/journal-file.h

@@ -2,6 +2,7 @@
 #pragma once
 
 #include <fcntl.h>
+#include <sys/stat.h>
 
 #include "compress.h"
 #include "forward.h"

src/libsystemd/sd-journal/mmap-cache.c

@@ -2,6 +2,7 @@
 
 #include <stdlib.h>
 #include <sys/mman.h>
+#include <sys/stat.h>
 
 #include "alloc-util.h"
 #include "bitfield.h"

src/run/run.c

@@ -5,6 +5,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/resource.h>
+#include <sys/stat.h>
 #include <unistd.h>
 
 #include "sd-bus.h"