vendor/bc: import version 6.3.1

This version adds a command to dc to query whether extended registers
are enabled or not.

(cherry picked from commit 61e1a12bb6c3bfdb0a4e499c88e8eaa2b548e427)

contrib/bc: merge from vendor release 6.2.2

This update fixes a few issues in history editing and the processing
of the "quit" function. The "quit" function will no longer cause bc
to exit when encountered in a script file (before any command from
the script has been executed).

New functions is_number(), is_string return 1 if the passed argument
is a number resp. a string. The asciify() function has been extended
to support the conversion of an array of numbers into a string.

Merge commit '1a63323d17fedb05b6962853e821c9d7c6b9853e'

usr.bin/bc: update to version 5.3.1

This version adds support for command line editing and history using
the libedit or readline libraries in addition to the line editing
features available in previous versions.

The version in the base system is configured to use libedit.

This allows to choose between emacs and vi line editing commands and
to use command overrides via a ~/.editrc file.

Merge commit 'bd54318046bfee055b140705a5cfd4148e78da07'

PR: 264010

MFC after: 2 weeks

usr.bin/bc: update to version 5.3.1

This version adds support for command line editing and history using
the libedit or readline libraries in addition to the line editing
features available in previous versions.

The version in the base system is configured to use libedit.

This allows to choose between emacs and vi line editing commands and
to use command overrides via a ~/.editrc file.

Merge commit 'bd54318046bfee055b140705a5cfd4148e78da07'

PR: 264010

MFC after: 2 weeks