Log Message:
www/guile-pg: Update to 0.50

- 0.50 | 2021-12-04

  - lob details bifurcated for "modern" Guile

    Guile 2.2 (and later, presumably) have ‘scm_c_make_port’ and in
    fact a whole rewrite of the ports extension mechanism.  Thus,
    all previous Guile-PG releases failed to build w/ Guile 2.2.
    Specifically, all the large object (lob) low-level details
    clashed irreconcilably.

    This release of Guile-PG now handles things by configure-time
    detection and selection of a suitably matching implementation.

    The file test/OK now includes an entry w/ a subheading of "other
    Guile" to show the range of supported Guile versions.  More to
    the point, if you build w/ Guile 2.2 and encounter problems,
    then please report it.

    NB: We haven't dipped into the Guile 3.0 waters yet.  Experience
    reports from those more adventurous are welcome, in any case.