Build procedure extproto() did not strip braces from header files, thus
possibly prepended them to true prototypes. This prevented the prototype to
be recognized as such.
The solution implemented here is to map braces to semicolons, effectively
considering them as potential prototype delimiters.
In addition, file os400/macros.h declares all procedures originally
defined as macros. It must not be used for real inclusion and is only
intended to be used as a `database' for macro wrapping procedures generation.
