side-effects from mesa-libs and ino64 updates ...?

I would appreciate observations about two difficulties that have 
surfaced for me since the mesa-libs and ino64 updates.  Likely these are 
pilot errors but I've not been able to identify the causes.

Here's the environment ...
FreeBSD silver 12.0-CURRENT FreeBSD 12.0-CURRENT #0 r318232: Fri May 12 
00:21:37 PDT 2017 root_at_silver:/usr/src/sys/amd64/compile/silver  amd64

/usr/src revision: 319159

/etc/src-env.conf
WITH_META_MODE=yes
NO_SILENT=yes

rm -r /usr/obj

1.  buildworld runs now fail:
Building /usr/obj/usr/src/share/colldef/es_MX.UTF-8.LC_COLLATE
--- all_subdir_lib ---
/usr/obj/usr/src/tmp/usr/lib/libgcc_s.so: undefined reference to 
`__gxx_personality_v0'
cc: error: linker command failed with exit code 1 (use -v to see invocation)

2. with ports as of:

Fetching snapshot metadata... done.
Updating from Sat May 27 09:42:54 PDT 2017 to Sun May 28 16:37:47 PDT 2017.

echo $QT_SELECT
qt5

attempting to re-install devel/py-qt5-core with
portmaster -d py27-qt5-core
yields
Error: Failed to determine the detail of your Qt installation.

Thanks for your thoughts.
Kevin Casey