Exposing functions: mono_custom_attrs_construct_by_type and mono_unity_error_convert_to_exception

* mono_custom_attrs_construct_by_type allows unity to have a chance at handling the error if one arises instead of fatally asserting
* mono_unity_error_convert_to_exception allows unity to take the provided MonoError and fetch the MonoException object within to log into the editor as the exception that was thrown.

This change has associated unity changes in order to fix (case 1255935)

mono/metadata/custom-attrs.c

@@ -1192,7 +1192,7 @@ create_custom_attr_data (MonoImage *image, MonoCustomAttrEntry *cattr, MonoError
 	HANDLE_FUNCTION_RETURN_OBJ (obj);
 }
 
-static MonoArray*
+MonoArray*
 mono_custom_attrs_construct_by_type (MonoCustomAttrInfo *cinfo, MonoClass *attr_klass, MonoError *error)
 {
 	MonoArray *result;

mono/metadata/reflection.h

@@ -90,6 +90,7 @@ MONO_RT_EXTERNAL_ONLY
 MONO_API MonoCustomAttrInfo* mono_reflection_get_custom_attrs_info (MonoObject *obj);
 MONO_RT_EXTERNAL_ONLY
 MONO_API MonoArray*  mono_custom_attrs_construct (MonoCustomAttrInfo *cinfo);
+MONO_API MonoArray* mono_custom_attrs_construct_by_type (MonoCustomAttrInfo *cinfo, MonoClass *attr_klass, MonoError *error);
 MONO_RT_EXTERNAL_ONLY
 MONO_API MonoCustomAttrInfo* mono_custom_attrs_from_index    (MonoImage *image, uint32_t idx);
 MONO_RT_EXTERNAL_ONLY

mono/metadata/unity-utils.c

@@ -870,6 +870,11 @@ MonoException* mono_unity_exception_get_marshal_directive(const char* msg)
 	return mono_exception_from_name_msg(mono_get_corlib(), "System.Runtime.InteropServices", "MarshalDirectiveException", msg);
 }
 
+MonoException* mono_unity_error_convert_to_exception (MonoError *error)
+{
+	return mono_error_convert_to_exception (error);
+}
+
 //defaults
 
 MonoClass* mono_unity_defaults_get_int_class()

mono/metadata/unity-utils.h

@@ -137,6 +137,7 @@ MonoObject* mono_unity_exception_get_inner_exception(MonoException *exc);
 MonoArray* mono_unity_exception_get_trace_ips(MonoException *exc);
 void mono_unity_exception_set_trace_ips(MonoException *exc, MonoArray *ips);
 MonoException* mono_unity_exception_get_marshal_directive(const char* msg);
+MONO_API MonoException* mono_unity_error_convert_to_exception(MonoError *error);
 
 //defaults
 MonoClass* mono_unity_defaults_get_int_class();