Disable warnings when compiling through dxc (#710)
Disable warnings when compiling through dxc (#710)

I had hoped to just disable certain warnings (false positives that trigger based on how Slang outputs HLSL code), but dxc doesn't support fine-grained control over warnings from the command line (we might investigate `#pragma`-based options later). There are enough user complaints about how downstream compiler errors come mixed with tons of distracting warnings that disabling them will lead to a better user experience for now.

This change also fixes a long-standing bug where apparently dxc does *not* guaranteee that the diagnostic blob it returns is nul-terminated (despite this convention being established by fxc), so that we need to nul-terminate it ourselves before emitting any diagnostic messages produced by dxc.
shader-slang/slang,shader-slang/slang,csyonghe/slang,csyonghe/slang,csyonghe/slang,shader-slang/slang