toolchain/55668: can not build current on current

[martin%NetBSD.org@localhost]

>Number:         55668
>Category:       toolchain
>Synopsis:       can not build current on current
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 17 19:30:00 +0000 2020
>Originator:     Martin Husemann
>Release:        NetBSD 9.99.73
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD seven-days-to-the-wolves.aprisoft.de 9.99.73 NetBSD 9.99.73 (GENERIC) #418: Thu Sep 17 13:45:44 CEST 2020 martin%seven-days-to-the-wolves.aprisoft.de@localhost:/work/src/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:

On a -current machine with all gcc 9 userland I can not build
-current for evbearmv5 with HAVE_GCC=8 (not sure if the latter
part is relevant).

The build "hangs" with a bunch of nbawk busy looping processes,
called for processing some objdump output (or so it seems).
I see several instances like this:

10715 pts/0 I+    0:00.00 | |           |                       |-- sh 
20776 pts/0 S+    0:00.04 | |           |                       | `-- /work/tools/bin/nbmake _THISDIR_ dependall 
26763 pts/0 I+    0:00.00 | |           |                       |   `-- sh 
25218 pts/0 S+    0:00.04 | |           |                       |     `-- /work/tools/bin/nbmake realall 
 1673 pts/0 I+    0:00.00 | |           |                       |       `-- sh 
27693 pts/0 I+    0:00.00 | |           |                       |         `-- sh 
15262 pts/0 R+   40:22.41 | |           |                       |           |-- /work/tools/bin/nbawk -f /work/tools/bin/nbawk 
19130 pts/0 I+    0:00.00 | |           |                       |           `-- /work/tools/bin/arm--netbsdelf-eabi-objdump --syms --reloc tmp.o (arm--netbsdelf-e)
19002 pts/0 I+    0:00.00 | |           |                       |-- sh 
[..]

and this stays the same for hours (lost patience and kille the build).

>How-To-Repeat:
s/a

>Fix:
n/a