core: Apply the same treatment to the in errno message in __igt_fail_assert()
core: Apply the same treatment to the in errno message in __igt_fail_assert()

Just like the it was done for the requirement message, display the errno
message only if errno is set, and display it at the end of the assert
message.

Reviewed-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>
Signed-off-by: Damien Lespiau <64bd3cb94f359c1a3ce68dae5e26b40578526277@intel.com>

erikarn/intel-gpu-tools,chenxianqin/intel-gpu-tools,yipdw/intel-gpu-tools,tiagovignatti/intel-gpu-tools,chenxianqin/intel-gpu-tools,mv0/intel-gpu-tools,erikarn/intel-gpu-tools,tiagovignatti/intel-gpu-tools,yipdw/intel-gpu-tools,yipdw/intel-gpu-tools,erikarn/intel-gpu-tools,chenxianqin/intel-gpu-tools,erikarn/intel-gpu-tools,chenxianqin/intel-gpu-tools,dlespiau/checkmate-test-igt,dlespiau/checkmate-test-igt,dlespiau/checkmate-test-igt,yipdw/intel-gpu-tools,tiagovignatti/intel-gpu-tools,mv0/intel-gpu-tools,tiagovignatti/intel-gpu-tools,mv0/intel-gpu-tools,dlespiau/checkmate-test-igt,mv0/intel-gpu-tools