Don't use path as variable name in colortbl.awk

Don't use path as variable name in colortbl.awk

Instead of using `argv[1]` to name the variable, we now always call it
`color_lib` in awk/colortbl.awk. The reason for this, is in some build
configurations, like the Visual Studio and CMake build, the full path to
the color_lib file is used. This resulted in the variable conaining
slashes, etc. Since the rest of the code already assumes this variable is
called `color_lib`, there is no problem with hard coding it in
colortbl.awk