tree-wide: move unsigned to the start of type declaration

Even though ISO C11 doesn't mandate in which order the type specifiers
should appear, having `unsigned` at the beginning of each type
declaration feels more natural and, more importantly, it unbreaks
Coccinelle, which has a hard time parsing `long unsigned` and others:

```
init_defs_builtins: /usr/lib64/coccinelle/standard.h
init_defs: /home/mrc0mmand/repos/systemd/coccinelle/macros.h
HANDLING: src/shared/mount-util.c
: 1: strange type1, maybe because of weird order: long unsigned
```

Most of the codebase already "complies", so let's fix the remaining
"offenders".

src/basic/process-util.c

@@ -645,7 +645,7 @@ int get_process_environ(pid_t pid, char **ret) {
 
 int get_process_ppid(pid_t pid, pid_t *ret) {
         _cleanup_free_ char *line = NULL;
-        long unsigned ppid;
+        unsigned long ppid;
         const char *p;
         int r;
 
@@ -688,7 +688,7 @@ int get_process_ppid(pid_t pid, pid_t *ret) {
         if (ppid == 0)
                 return -EADDRNOTAVAIL;
 
-        if ((pid_t) ppid < 0 || (long unsigned) (pid_t) ppid != ppid)
+        if ((pid_t) ppid < 0 || (unsigned long) (pid_t) ppid != ppid)
                 return -ERANGE;
 
         if (ret)