always add memory streams to stdio open file list

per interpretation for austin group issue #626, fflush(0) and exit()
must block waiting for a lock if another thread has locked a memory
stream with flockfile. this adds some otherwise-unnecessary
synchronization cost to use of memory streams, but there was already a
synchronization cost calling malloc anyway.

previously the stream was only added to the open file list in
single-threaded programs, so that upon subsequent call to
pthread_create, locking could be turned on for the stream.

src/stdio/fmemopen.c

@@ -108,12 +108,13 @@ FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode)
 	f->seek = mseek;
 	f->close = mclose;
 
-	if (!libc.threaded) {
+	if (!libc.threaded) f->lock = -1;
-		f->lock = -1;
+
-		f->next = libc.ofl_head;
+	OFLLOCK();
-		if (libc.ofl_head) libc.ofl_head->prev = f;
+	f->next = libc.ofl_head;
-		libc.ofl_head = f;
+	if (libc.ofl_head) libc.ofl_head->prev = f;
-	}
+	libc.ofl_head = f;
+	OFLUNLOCK();
 
 	return f;
 }

src/stdio/open_memstream.c

@@ -77,12 +77,13 @@ FILE *open_memstream(char **bufp, size_t *sizep)
 	f->seek = ms_seek;
 	f->close = ms_close;
 
-	if (!libc.threaded) {
+	if (!libc.threaded) f->lock = -1;
-		f->lock = -1;
+
-		f->next = libc.ofl_head;
+	OFLLOCK();
-		if (libc.ofl_head) libc.ofl_head->prev = f;
+	f->next = libc.ofl_head;
-		libc.ofl_head = f;
+	if (libc.ofl_head) libc.ofl_head->prev = f;
-	}
+	libc.ofl_head = f;
+	OFLUNLOCK();
 
 	return f;
 }

src/stdio/open_wmemstream.c

@@ -79,12 +79,13 @@ FILE *open_wmemstream(wchar_t **bufp, size_t *sizep)
 	f->seek = wms_seek;
 	f->close = wms_close;
 
-	if (!libc.threaded) {
+	if (!libc.threaded) f->lock = -1;
-		f->lock = -1;
+
-		f->next = libc.ofl_head;
+	OFLLOCK();
-		if (libc.ofl_head) libc.ofl_head->prev = f;
+	f->next = libc.ofl_head;
-		libc.ofl_head = f;
+	if (libc.ofl_head) libc.ofl_head->prev = f;
-	}
+	libc.ofl_head = f;
+	OFLUNLOCK();
 
 	return f;
 }