vendor/bc: upgrade to version 7.0.2

This update fixes exiting from an interactive bc session with ^D on
FreeBSD and Linux when using editline.

This bug was caused by the macOS fix for editline in version 7.0.0,
which has been reverted in this version.

(cherry picked from commit c2c85f88902d18d2e9702381f1628112e15a5c3c)

MFC after: 3 days
Reported by: mack@macktronics.com