libobs: Add config_has_(user|default)_value functions

Similar to obs_data_has_(user_value|default|autoselect), these allow
library users to distinguish between user config values and default
values

libobs/util/config-file.c

@@ -598,3 +598,16 @@ double config_get_default_double(config_t config, const char *section,
 
 	return 0.0;
 }
+
+bool config_has_user_value(config_t config, const char *section,
+		const char *name)
+{
+	return config_find_item(&config->sections, section, name) != NULL;
+}
+
+bool config_has_default_value(config_t config, const char *section,
+		const char *name)
+{
+	return config_find_item(&config->defaults, section, name) != NULL;
+}
+

libobs/util/config-file.h

@@ -112,6 +112,11 @@ EXPORT bool config_get_default_bool(config_t config, const char *section,
 EXPORT double config_get_default_double(config_t config, const char *section,
 		const char *name);
 
+EXPORT bool config_has_user_value(config_t config, const char *section,
+		const char *name);
+EXPORT bool config_has_default_value(config_t config, const char *section,
+		const char *name);
+
 #ifdef __cplusplus
 }
 #endif