Troubles building world on stable/13

The last few attempts to build world on a Pi3 running stable/13 have
stopped with something like:

--- all_subdir_lib/googletest/gmock ---
===> lib/googletest/gmock (all)
Building /usr/obj/usr/src/arm64.aarch64/lib/googletest/gmock/gmock-all.o
--- gmock-all.o ---
PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: c++ -target aarch64-unknown-freebsd13.0 --sysroot=/usr/obj/usr/src/arm64.aarch64/tmp -B/usr/obj/usr/src/arm64.aarch64/tmp/usr/bin -O2 -pipe -fno-common -g -Wno-format-zero-length -fstack-protector-strong -Wsystem-headers -Werror -Wall -Wno-format-y2k -W -Wno-unused-parameter -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow -Wunused-parameter -Wcast-align -Wchar-subscripts -Wredundant-decls -Wmissing-variable-declarations -Wno-empty-body -Wno-string-plus-int -Wno-unused-const-variable -Wno-error=unused-but-set-variable -Qunused-arguments -I/usr/obj/usr/src/arm64.aarch64/tmp/usr/include/private -I/usr/src/contrib/googletest/googlemock/include -I/usr/src/contrib/googletest/googlemock -I/usr/src/contrib/googletest/googletest/include -g -std
 =c++11 -Wno-deprecated-declarations -Wno-deprecated-copy -Wno-c++11-extensions -c /usr/src/contrib/googletest/googlemock/src/gmock-all.cc -o gmock-all.o
1.      /usr/obj/usr/src/arm64.aarch64/tmp/usr/include/private/gtest/internal/gtest-type-util.h:1125:53: current parser token '{'
2.      /usr/obj/usr/src/arm64.aarch64/tmp/usr/include/private/gtest/internal/gtest-type-util.h:58:1: parsing namespace 'testing'
--- all_subdir_lib/clang ---
Building /usr/obj/usr/src/arm64.aarch64/lib/clang/libllvm/X86GenEVEX2VEXTables.inc
Building /usr/obj/usr/src/arm64.aarch64/lib/clang/libllvm/X86GenFastISel.inc
--- all_subdir_lib/googletest ---
#0 0x0000000004112640 PrintStackTrace /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:565:13
#1 0x0000000004110a84 __cxx_atomic_store<CallbackAndCookie::Status> /usr/obj/usr/src/arm64.aarch64/tmp/usr/include/c++/v1/atomic:996:5
#2 0x0000000004110a84 store /usr/obj/usr/src/arm64.aarch64/tmp/usr/include/c++/v1/atomic:1617:10
#3 0x0000000004110a84 RunSignalHandlers /usr/src/contrib/llvm-project/llvm/lib/Support/Signals.cpp:99:16
#4 0x00000000040b4f08 HandleCrash /usr/src/contrib/llvm-project/llvm/lib/Support/CrashRecoveryContext.cpp:76:5
#5 0x00000000040b4f08 CrashRecoverySignalHandler /usr/src/contrib/llvm-project/llvm/lib/Support/CrashRecoveryContext.cpp:389:51
#6 0x00000000452bad80 handle_signal /usr/src/lib/libthr/thread/thr_sig.c:0:3
c++: error: clang frontend command failed with exit code 139 (use -v to see invocation)
FreeBSD clang version 13.0.0 ([email protected]:llvm/llvm-project.git llvmorg-13.0.0-0-gd7b669b3a303)
Target: aarch64-unknown-freebsd13.0
Thread model: posix
InstalledDir: /usr/bin
c++: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
c++: note: diagnostic msg: /tmp/gmock-all-836ef8.cpp
c++: note: diagnostic msg: /tmp/gmock-all-836ef8.sh
c++: note: diagnostic msg: 

********************
*** [gmock-all.o] Error code 139

make[6]: stopped in /usr/src/lib/googletest/gmock
.ERROR_TARGET='gmock-all.o'
.ERROR_META_FILE='/usr/obj/usr/src/arm64.aarch64/lib/googletest/gmock/gmock-all.o.meta'
.MAKE.LEVEL='6'
MAKEFILE=''
.MAKE.MODE='meta missing-filemon=yes missing-meta=yes silent=yes verbose'

make[4]: stopped in /usr/src/lib
--- all_subdir_lib/clang ---

FWIW, filemon is enabled in /boot/loader.conf and the build command was
make -j2 -DWITH_META_MODE  buildworld > buildworld.log

This doesn't appear to be ARM-specific in any obvious way, but it might
be, so I'm posting here first.

Thanks for reading,

bob prohaska