Some empty qemu_x86 output when running code coverage using sanity_check

[cinlyooi-intel]

To Reproduce
Steps to reproduce the behavior:

# To generate the errors
scripts/sanitycheck --coverage 
   --coverage-platform mps2_an385 -p mps2_an385 
   --coverage-platform qemu_x86 -p qemu_x86  
   --coverage-platform qemu_x86_nommu  -p qemu_x86_nommu -
   -gcov-tool /opt/zephyr-sdk-0.10.0/i586-zephyr-elf/bin/i586-zephyr-elf-gcov \
   -T tests/kernel -T tests/subsys/logging | tee output.log

# the files to open are
# sanity-out/qemu_x86/tests/kernel/stack/stack_usage/kernel.stack.usage/run.log
# sanity-out/qemu_x86/tests/kernel/stack/stack_api/kernel.stack/run.log
# sanity-out/qemu_x86/tests/kernel/mem_protect/stackprot/kernel.memory_protection/run.log
# sanity-out/qemu_x86/tests/kernel/mem_pool/mempool_api/kernel.memory_pool/run.log

Screenshots or console output

...
make[4]: Leaving directory '/home/cinlyooi/tests/zephyrproject/zephyr/sanity-out/qemu_x86/tests/kernel/stack/stack_usage/kernel.stack.usage'
make[4]: Entering directory '/home/cinlyooi/tests/zephyrproject/zephyr/sanity-out/qemu_x86/tests/kernel/stack/stack_usage/kernel.stack.usage'
[100%] [QEMU] CPU: qemu32,+nx,+pae
QEMU 3.1.0 monitor - type 'help' for more information
(qemu) make[4]: *** [zephyr/CMakeFiles/run.dir/build.make:58: zephyr/CMakeFiles/run] Error 1
make[4]: Target 'zephyr/CMakeFiles/run.dir/build' not remade because of errors.
make[4]: Leaving directory '/home/cinlyooi/tests/zephyrproject/zephyr/sanity-out/qemu_x86/tests/kernel/stack/stack_usage/kernel.stack.usage'
make[3]: *** [CMakeFiles/Makefile2:317: zephyr/CMakeFiles/run.dir/all] Error 2
...

Environment (please complete the following information):

• OS: fedora29
• Toolchain zephyr
• Commit SHA or Version used: 0734b4f