Revert "Vulkan: Use VK_NV_glsl extension where available, and skip glslang"

This reverts commit d23fd17e1a.

Dynamic sampler indexing is broken in VK_NV_glsl as of 385.41. The
performance gap doesn't seem to be as wide with the updated driver, so
to save maintaining two code paths, it's easier to just drop the
extension support completely.

Source/Core/VideoBackends/Vulkan/Util.h

@@ -61,16 +61,20 @@ void ExecuteCurrentCommandsAndRestoreState(bool execute_off_thread,
 VkShaderModule CreateShaderModule(const u32* spv, size_t spv_word_count);
 
 // Compile a vertex shader and create a shader module, discarding the intermediate SPIR-V.
-VkShaderModule CompileAndCreateVertexShader(const std::string& source_code);
+VkShaderModule CompileAndCreateVertexShader(const std::string& source_code,
+                                            bool prepend_header = true);
 
 // Compile a geometry shader and create a shader module, discarding the intermediate SPIR-V.
-VkShaderModule CompileAndCreateGeometryShader(const std::string& source_code);
+VkShaderModule CompileAndCreateGeometryShader(const std::string& source_code,
+                                              bool prepend_header = true);
 
 // Compile a fragment shader and create a shader module, discarding the intermediate SPIR-V.
-VkShaderModule CompileAndCreateFragmentShader(const std::string& source_code);
+VkShaderModule CompileAndCreateFragmentShader(const std::string& source_code,
+                                              bool prepend_header = true);
 
 // Compile a compute shader and create a shader module, discarding the intermediate SPIR-V.
-VkShaderModule CompileAndCreateComputeShader(const std::string& source_code);
+VkShaderModule CompileAndCreateComputeShader(const std::string& source_code,
+                                             bool prepend_header = true);
 }
 
 // Utility shader vertex format