[SPIR-V] Fatal error in compilation when using nointerpolation modifier

[Mr-Wiseguy]

The following code fails to compile when emitting SPIR-V, but compiles fine when emitting DXIL:

void PSMain(nointerpolation in float4 flatColor : COLOR0, out float4 resultColor : SV_TARGET)
{
    resultColor = flatColor;
}

The error is as follows:

fatal error: generated SPIR-V is invalid: OpStore Pointer <id> '3[%out_var_SV_TARGET]'s type does not match Object <id> '14[%14]'s type.
  OpStore %out_var_SV_TARGET %14

[s-perron]

Duplicate of #5270.