NetBSD 10.0 - configure test process hang

Hi!

I have swapped CPU's between my SS10 with 9.4 and SS20 with 10.0 
(HyperSPARC vs SuperSPARC) and testing a couple of compilations to see.

On the SS20 (now with 2x SuperSPARC) I started compiling basic packages 
I need for 10.0 - it is just a little more stable than with HyperSPARC 
so things progress more.
Now I got something never happened to me - process hang:

Configure of bash hangs this way:
checking whether pthread_rwlock_rdlock prefers a writer to a reader...

hangs forever, I left it overnight, but nothing. no CPU usage and no 
processes in top.

I suppose it is this:

11361 root      85    0    24M 1336K nanosl/0    0:02  0.00%  0.00% conftest

deadlock? starved?

I see no errors in dmesg and serial console I left attached show snothing.

legolas: {31} ps -ax | grep conf
  7329 pts/1 S+   0:00.07 grep conf
10191 pts/2 I+   0:04.19 /bin/sh ./configure LOCAL_LDFLAGS=-Wl,-E 
--enable-alias --enable-array-variables --enable-
11361 pts/2 Sl+  0:02.49 ./conftest
14133 pts/2 I+   0:00.02 /bin/sh ./configure LOCAL_LDFLAGS=-Wl,-E 
--enable-alias --enable-array-variables --enable-

I wonder why there are two configures? I understand parallelism of 2, 
but maybe parallel tests not configures.

Anyway, I try to attach to it with gdb:
  gdb --pid=11361

but this hangs, nothing happens! I was able to "ctrl-c" configure but 
gdb then still hangs :)

I relaunched make... and it passed through, so it is a "temporary" hang, 
which is of course worse because hard to debug. Bash then completed 
compilation & installation.
Continuing with other stuff to "stress" more

Riccardo