contrib/bc: update to version 4.0.2

contrib/bc: update to version 4.0.2

Merge commit '2858419a0ee2b8f5827de72c00618bcd69ebc5fc'

This update fixes the initialization of "scale" to 20 if started with
-l and the initial statement leads to an error (e.g. contains a syntax
error). Scale was initialized to 0 in that case.

Another change is the support of job control in interactive mode with
line editing enabled. The control characters have been interpreted as
editing commands only, prior to this version.

MFC after:	3 days