SPV: Give error on not assigning locations to I/O.

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.

gtests/Link.FromFile.Vk.cpp

@@ -60,6 +60,7 @@ TEST_P(LinkTestVulkan, FromFile)
         shaders.emplace_back(
                 new glslang::TShader(GetShaderStage(GetSuffix(fileNames[i]))));
         auto* shader = shaders.back().get();
+        shader->setAutoMapLocations(true);
         compile(shader, contents, "", controls);
         result.shaderResults.push_back(
             {fileNames[i], shader->getInfoLog(), shader->getInfoDebugLog()});

gtests/TestFixture.h

@@ -202,6 +202,7 @@ public:
         const EShLanguage kind = GetShaderStage(GetSuffix(shaderName));
 
         glslang::TShader shader(kind);
+        shader.setAutoMapLocations(true);
         shader.setFlattenUniformArrays(flattenUniformArrays);
 
         bool success = compile(&shader, code, entryPointName, controls);
@@ -254,6 +255,7 @@ public:
         shader.setShiftUboBinding(baseUboBinding);
         shader.setShiftSsboBinding(baseSsboBinding);
         shader.setAutoMapBindings(autoMapBindings);
+        shader.setAutoMapLocations(true);
         shader.setFlattenUniformArrays(flattenUniformArrays);
 
         bool success = compile(&shader, code, entryPointName, controls);
@@ -295,6 +297,8 @@ public:
         const EShLanguage kind = GetShaderStage(GetSuffix(shaderName));
 
         glslang::TShader shader(kind);
+        shader.setAutoMapLocations(true);
+
         bool success = compile(&shader, code, entryPointName, controls);
 
         glslang::TProgram program;