GPU: Add HQ normals workaround.

This change makes it possible for platforms to only support high quality
normal rendering. This is part of {T82856} where current AMD drivers
running on the polaris architecture does not support the low quality
setting due to a driver bug.

In a next commit the work around will be enabled.

source/blender/gpu/GPU_capabilities.h

@@ -43,6 +43,7 @@ int GPU_texture_size_with_limit(int res);
 bool GPU_mip_render_workaround(void);
 bool GPU_depth_blitting_workaround(void);
 bool GPU_use_main_context_workaround(void);
+bool GPU_use_hq_normals_workaround(void);
 bool GPU_crappy_amd_driver(void);
 
 bool GPU_shader_image_load_store_support(void);

source/blender/gpu/intern/gpu_capabilities.cc

@@ -102,6 +102,11 @@ bool GPU_crappy_amd_driver(void)
   return GCaps.broken_amd_driver;
 }
 
+bool GPU_use_hq_normals_workaround(void)
+{
+  return GCaps.use_hq_normals_workaround;
+}
+
 bool GPU_shader_image_load_store_support(void)
 {
   return GCaps.shader_image_load_store_support;

source/blender/gpu/intern/gpu_capabilities_private.hh

@@ -48,6 +48,7 @@ struct GPUCapabilities {
   bool depth_blitting_workaround = false;
   bool use_main_context_workaround = false;
   bool broken_amd_driver = false;
+  bool use_hq_normals_workaround = false;
   /* Vulkan related workarounds. */
 };