benchmarks: Do not install to system-wide bin/
benchmarks: Do not install to system-wide bin/

These benchmarks are first-and-foremost development tools, not aimed at
general users. As such they should not be installed into the system-wide
bin/ directory, but installed into libexec/.

v2: Now actually install beneath ${libexec}

Signed-off-by: Chris Wilson <711c73f64afdce07b7e38039a96d2224209e9a6c@chris-wilson.co.uk>

tiagovignatti/intel-gpu-tools,tiagovignatti/intel-gpu-tools,chenxianqin/intel-gpu-tools,mv0/intel-gpu-tools,chenxianqin/intel-gpu-tools,mv0/intel-gpu-tools,chenxianqin/intel-gpu-tools,chenxianqin/intel-gpu-tools,mv0/intel-gpu-tools,tiagovignatti/intel-gpu-tools,tiagovignatti/intel-gpu-tools,mv0/intel-gpu-tools