Move some external files to external/ folder (#744)

It is lot easier to work with automatic formatters if we have external
files in different folder. For some tools we can example just exclude
external all together.

Co-authored-by: Kari Argillander <kari.argillander@fidelix.com>

ports/bdk-atxx4-mstp/external/crossworks/stdbool.h

@@ -0,0 +1,20 @@
+#ifndef STDBOOL_H
+#define STDBOOL_H
+
+/* C99 Boolean types for compilers without C99 support */
+
+#ifndef __cplusplus
+typedef char _Bool;
+#ifndef bool
+#define bool _Bool
+#endif
+#ifndef true
+#define true 1
+#endif
+#ifndef false
+#define false 0
+#endif
+#define __bool_true_false_are_defined 1
+#endif
+
+#endif