Also, provides an option to auto-assign locations.
Existing tests use this option, to avoid the error message,
however, it is not fully implemented yet.
Previously, the binding auto-mapping facility was free to use any unused
binding. This change makes auto-bindings use the same offset value as
explicit bindings.
This PR adds a GLSL equivalent to the HLSL binding mapping tests for offsets and auto-numbering.
The shaders are as equivalent as possible. The bindings of the base results match exactly
between the two.
