bc: upgrade 1.08.1 -> 1.08.2

bc: upgrade 1.08.1 -> 1.08.2

Changes:
  - Remove last vestages of K&R C; this allows gcc-15+ to compile
    the code without special options.
  - Some typo and formatting fixes in the documentation.

The above change also allowed dropping the relevant patch, that fixed
gcc15 compatibility: 0001-getopt-Add-missing-params-to-getopt-getenv-signature.patch

License-Update: added copyright years to the file header.

Signed-off-by: Gyorgy Sarvari <skandigraun@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>