Determining if the include file pthread.h exists failed with the following output:
Change Dir: /srv/storage/autobuild/run/instance-1/output-1/build/qpid-proton-0.33.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_5adac/fast && make[1]: Entering directory '/srv/storage/autobuild/run/instance-1/output-1/build/qpid-proton-0.33.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_5adac.dir/build.make CMakeFiles/cmTC_5adac.dir/build
make[2]: Entering directory '/srv/storage/autobuild/run/instance-1/output-1/build/qpid-proton-0.33.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_5adac.dir/CheckIncludeFile.c.o
/srv/storage/autobuild/run/instance-1/output-1/host/bin/arm-linux-gcc --sysroot=/srv/storage/autobuild/run/instance-1/output-1/host/arm-buildroot-linux-uclibcgnueabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2   -DNDEBUG   -o CMakeFiles/cmTC_5adac.dir/CheckIncludeFile.c.o   -c /srv/storage/autobuild/run/instance-1/output-1/build/qpid-proton-0.33.0/CMakeFiles/CMakeTmp/CheckIncludeFile.c
/srv/storage/autobuild/run/instance-1/output-1/build/qpid-proton-0.33.0/CMakeFiles/CMakeTmp/CheckIncludeFile.c:1:10: fatal error: pthread.h: No such file or directory
    1 | #include <pthread.h>
      |          ^~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/cmTC_5adac.dir/build.make:66: CMakeFiles/cmTC_5adac.dir/CheckIncludeFile.c.o] Error 1
make[2]: Leaving directory '/srv/storage/autobuild/run/instance-1/output-1/build/qpid-proton-0.33.0/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:121: cmTC_5adac/fast] Error 2
make[1]: Leaving directory '/srv/storage/autobuild/run/instance-1/output-1/build/qpid-proton-0.33.0/CMakeFiles/CMakeTmp'