Build: Fix build when NV_EXTENSIONS is not enabled.
diff --git a/SPIRV/GlslangToSpv.cpp b/SPIRV/GlslangToSpv.cpp
index 4833cd7..a167702 100755
--- a/SPIRV/GlslangToSpv.cpp
+++ b/SPIRV/GlslangToSpv.cpp
@@ -2467,7 +2467,7 @@
         return true;
     if ((member.getFieldName() == "gl_ViewportIndex" || member.getFieldName() == "gl_Layer") &&
         extensions.find(glslang::E_GL_ARB_shader_viewport_layer_array) == extensions.end() &&
-        extensions.find(glslang::E_GL_NV_viewport_array2) == extensions.end())
+        extensions.find("GL_NV_viewport_array2") == extensions.end())
         return true;
 
     return false;