SPV: Add option for controling when the SPIRV-Tools validator is used.

SPIRV/GlslangToSpv.cpp

@@ -7015,7 +7015,8 @@ void GlslangToSpv(const glslang::TIntermediate& intermediate, std::vector<unsign
     it.dumpSpv(spirv);
 
 #if ENABLE_OPT
-    SpirvToolsValidate(intermediate, spirv, logger);
+    if (options->validate)
+        SpirvToolsValidate(intermediate, spirv, logger);
 
     // If from HLSL, run spirv-opt to "legalize" the SPIR-V for Vulkan
     // eg. forward and remove memory writes of opaque types.

SPIRV/SpvTools.h

@@ -51,11 +51,12 @@ namespace glslang {
 
 struct SpvOptions {
     SpvOptions() : generateDebugInfo(false), disableOptimizer(true),
-        optimizeSize(false), disassemble(false) { }
+        optimizeSize(false), disassemble(false), validate(false) { }
     bool generateDebugInfo;
     bool disableOptimizer;
     bool optimizeSize;
     bool disassemble;
+    bool validate;
 };
 
 #if ENABLE_OPT