GPUShader: Expose create_info getter

This allows to check if a create_info extists based on its name.

source/blender/gpu/GPU_shader.h

@@ -71,6 +71,8 @@ GPUShader *GPU_shader_create_ex(const char *vertcode,
 GPUShader *GPU_shader_create_from_info(const GPUShaderCreateInfo *_info);
 GPUShader *GPU_shader_create_from_info_name(const char *info_name);
 
+const GPUShaderCreateInfo *GPU_shader_create_info_get(const char *info_name);
+
 struct GPU_ShaderCreateFromArray_Params {
   const char **vert, **geom, **frag, **defs;
 };

source/blender/gpu/intern/gpu_shader.cc

@@ -249,6 +249,11 @@ GPUShader *GPU_shader_create_compute(const char *computecode,
                               shname);
 }
 
+const GPUShaderCreateInfo *GPU_shader_create_info_get(const char *info_name)
+{
+  return gpu_shader_create_info_get(info_name);
+}
+
 GPUShader *GPU_shader_create_from_info_name(const char *info_name)
 {
   using namespace blender::gpu::shader;

source/blender/gpu/intern/gpu_shader_create_info.cc

@@ -302,6 +302,7 @@ const GPUShaderCreateInfo *gpu_shader_create_info_get(const char *info_name)
 {
   if (g_create_infos->contains(info_name) == false) {
     printf("Error: Cannot find shader create info named \"%s\"\n", info_name);
+    return nullptr;
   }
   ShaderCreateInfo *info = g_create_infos->lookup(info_name);
   return reinterpret_cast<const GPUShaderCreateInfo *>(info);