posix: system_database_r: remove invalid compilation filters

pwd.c and grp.c both had incorrect preprocessor guards around the stubs
that they were implementing. Functions were surrounded by

```cpp
..
```

Which is not at all accurate, since that subprofiling option group is
`(CONFIG_)POSIX_SYSTEM_DATABASE_R`.D

Remove the guards, since they are invalid anyway, and at most an
application will link properly.

Signed-off-by: Chris Friedt <[email protected]>

Author: cfriedt

lib/posix/options/grp.c

@@ -9,8 +9,6 @@
 #include <zephyr/sys/util.h>
 #include <zephyr/posix/grp.h>
 
-#ifdef CONFIG_POSIX_THREAD_SAFE_FUNCTIONS
-
 int getgrnam_r(const char *name, struct group *grp, char *buffer, size_t bufsize,
 	       struct group **result)
 {
@@ -33,5 +31,3 @@ int getgrgid_r(gid_t gid, struct group *grp, char *buffer, size_t bufsize, struc
 
 	return ENOSYS;
 }
-
-#endif /* CONFIG_POSIX_THREAD_SAFE_FUNCTIONS */

lib/posix/options/pwd.c

@@ -9,8 +9,6 @@
 #include <zephyr/sys/util.h>
 #include <zephyr/posix/pwd.h>
 
-#ifdef CONFIG_POSIX_THREAD_SAFE_FUNCTIONS
-
 int getpwnam_r(const char *nam, struct passwd *pwd, char *buffer, size_t bufsize,
 	       struct passwd **result)
 {
@@ -33,5 +31,3 @@ int getpwuid_r(uid_t uid, struct passwd *pwd, char *buffer, size_t bufsize, stru
 
 	return ENOSYS;
 }
-
-#endif /* CONFIG_POSIX_THREAD_SAFE_FUNCTIONS */