Implement functions to get stdin, stdout & stderr

src/os/file/posix/file_posix.c

@@ -49,13 +49,20 @@ wapp_intern i32 file_seek_origins[FILE_SEEK_ORIGIN_COUNT] = {
 	[WAPP_SEEK_END]     = SEEK_END,
 };
 
-wapp_intern WFile _STDIN  = { .fd = STDIN_FILENO };
-wapp_intern WFile _STDOUT = { .fd = STDOUT_FILENO };
-wapp_intern WFile _STDERR = { .fd = STDERR_FILENO };
+WFile *wapp_file_stdin(void) {
+	wapp_persist WFile _stdin  = { .fd = STDIN_FILENO };
+	return &_stdin;
+}
 
-WFile *WF_STDIN  = &_STDIN;
-WFile *WF_STDOUT = &_STDOUT;
-WFile *WF_STDERR = &_STDERR;
+WFile *wapp_file_stdout(void) {
+	wapp_persist WFile _stdout = { .fd = STDOUT_FILENO };
+	return &_stdout;
+}
+
+WFile *wapp_file_stderr(void) {
+	wapp_persist WFile _stderr = { .fd = STDERR_FILENO };
+	return &_stderr;
+}
 
 WFile *_file_open(const Allocator *allocator, Str8RO *filepath, FileAccessMode mode) {
 	wapp_persist c8 tmp[WAPP_PATH_MAX] = {0};