toolchain/54344: current build invokes gawk and causes strange warnings

[martin%NetBSD.org@localhost]

>Number:         54344
>Category:       toolchain
>Synopsis:       current build invokes gawk and causes strange warnings
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jul 05 16:40:00 +0000 2019
>Originator:     Martin Husemann
>Release:        NetBSD 8.99.50
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD night-owl.duskware.de 8.99.50 NetBSD 8.99.50 (NIGHT-OWL) #681: Fri Jul 5 18:05:36 CEST 2019 martin%night-owl.duskware.de@localhost:/usr/src/sys/arch/amd64/compile/NIGHT-OWL amd64
Architecture: x86_64
Machine: amd64
>Description:

Found in my build log:

===> build.sh command:    ./build.sh -u -O /usr/obj -E -D / -T /usr/tools -V MKCTF=no -V MKDTRACE=no -V MKLLVMRT=no -j 6 -V BUILDINFO=Build locally, cvs.netbsd.org source tree date: 2019-07-05 16:12 UTC -V MKDEBUG=yes build
[..]
--- bt_close.d ---
#    create  compat/bt_close.d
/usr/obj/tools/host-mkdep/host-mkdep -f bt_close.d.tmp  --      -I. -I./include -I/usr/src/tools/compat -I/usr/src/tools/compat/sys -DHAVE_NBTOOL_CONFIG_H=1 -D_FILE_OFFSET_BITS=64 -D__DBINTERFACE_PRIVATE     /usr/src/tools/compat/../../lib/libc/db/btree/bt_close.c &&  mv -f bt_close.d.tmp bt_close.d
--- bt_debug.d ---
gawk: cmd. line:4: warning: regexp escape sequence `\"' is not a known regexp operator
--- atoll.d ---
gawk: cmd. line:4: warning: regexp escape sequence `\"' is not a known regexp operator
--- bt_delete.d ---
gawk: cmd. line:4: warning: regexp escape sequence `\"' is not a known regexp operator
--- basename.d ---
gawk: cmd. line:4: warning: regexp escape sequence `\"' is not a known regexp operator
--- bt_close.d ---
gawk: cmd. line:4: warning: regexp escape sequence `\"' is not a known regexp operator
[..]

I guess at this stage no gawk should be invoked (and the only awk binary in
my path is /usr/bin/awk which is not gawk). The other awk resonably
invoked is /usr/tools/bin/nbawk which also is not gawk.

>How-To-Repeat:
s/a

>Fix:
n/a