printexc: a catch-all exception handler

value f: ('a -> 'b) -> 'a -> 'b

printexc__f fn x applies fn to x and returns the result. If the evaluation of fn x raises any exception, the name of the exception is printed on standard error output, and the programs aborts with exit code 2. Typical use is printexc__f main (), where main, with type unit->unit, is the entry point of a standalone program, to catch and print stray exceptions. For printexc__f to work properly, the program must have been linked with the -g option.