pkg/55624: Installing gcc > 8 breaks pkgsrc

[bruce.lilly+nbsd%gmail.com@localhost]

>Number:         55624
>Category:       pkg
>Synopsis:       Installing gcc > 8 breaks pkgsrc
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Aug 29 15:50:00 +0000 2020
>Originator:     Bruce Lilly
>Release:        9.0
>Organization:
>Environment:
NetBSD cq60-615dx.blilly.net 9.0 NetBSD 9.0 (GENERIC) #0: Fri Feb 14 00:06:28 UTC 2020  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64 x86_64 Intel 686-class NetBSD
>Description:
If gcc version > 8 is installed, attempts to build packages from source fail.  Example:
bruce@cq60-615dx:/usr/pkgsrc/misc/ascii# bmake         
ERROR: This package has set PKG_FAIL_REASON:
ERROR: Unable to satisfy dependency: gcc8>=10.1.0
*** Error code 1

Stop.
bmake: stopped in /usr/pkgsrc/misc/ascii
>How-To-Repeat:
Fresh install (not upgrade) of NetBSD 9.0
Install gcc9 or later (see pkg/55623)
Try to build some package from source
>Fix:
Fix is unknown, but the problem appears to be in
/usr/pkgsrc/mk/compiler/gcc.mk
which (if I'm reading it correctly)
doesn't seem to have any provision for gcc9 or gcc 10
(or gcc11...)
even though pkgsrc contains packages for gcc9 and gcc10