Determining if the include file io.h exists failed with the following output:
Change Dir: /home/buildroot/build/instance-2/output/build/cmocka-1.1.5/buildroot-build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_ee8c9/fast"
make[1]: Entering directory '/home/buildroot/build/instance-2/output/build/cmocka-1.1.5/buildroot-build/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_ee8c9.dir/build.make CMakeFiles/cmTC_ee8c9.dir/build
make[2]: Entering directory '/home/buildroot/build/instance-2/output/build/cmocka-1.1.5/buildroot-build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_ee8c9.dir/CheckIncludeFile.c.o
/home/buildroot/build/instance-2/output/host/bin/riscv64-buildroot-linux-musl-gcc --sysroot=/home/buildroot/build/instance-2/output/host/riscv64-buildroot-linux-musl/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2   -DNDEBUG -fPIE   -o CMakeFiles/cmTC_ee8c9.dir/CheckIncludeFile.c.o   -c /home/buildroot/build/instance-2/output/build/cmocka-1.1.5/buildroot-build/CMakeFiles/CMakeTmp/CheckIncludeFile.c
/home/buildroot/build/instance-2/output/build/cmocka-1.1.5/buildroot-build/CMakeFiles/CMakeTmp/CheckIncludeFile.c:1:10: fatal error: io.h: No such file or directory
 #include <io.h>
          ^~~~~~
compilation terminated.
CMakeFiles/cmTC_ee8c9.dir/build.make:65: recipe for target 'CMakeFiles/cmTC_ee8c9.dir/CheckIncludeFile.c.o' failed
make[2]: *** [CMakeFiles/cmTC_ee8c9.dir/CheckIncludeFile.c.o] Error 1
make[2]: Leaving directory '/home/buildroot/build/instance-2/output/build/cmocka-1.1.5/buildroot-build/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_ee8c9/fast' failed
make[1]: *** [cmTC_ee8c9/fast] Error 2
make[1]: Leaving directory '/home/buildroot/build/instance-2/output/build/cmocka-1.1.5/buildroot-build/CMakeFiles/CMakeTmp'