vendor/bc: update to upstream commit ca53adf83b7a

The filter_text function in scripts/functions.sh in version 5.3.3 had
commented out a "rm" command, probably for debugging purposes. This
caused temporary files to persist in /tmp when the bc program had been
built.

This commit fixes the build process with no change of the resulting
artefacts.

(cherry picked from commit 1576f66712876ee8b0fcc8b35fb062e1813b4fc0)

MFC after: 3 days