loader: Add dependency fields to module structures.

* Declare 'requires' and 'enhances' text fields on module info structure.
* Rename 'nonoptreq' to 'optional_modules'.
* Update doxygen comments.

Still need to investigate dependencies among modules I cannot compile.

Change-Id: I3ad9547a0a6442409ff4e352a6d897bef2cc04bf

tests/test_ari.c

@@ -573,5 +573,5 @@ static int load_module(void)
 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "ARI testing",
 	.load = load_module,
 	.unload = unload_module,
-	.nonoptreq = "res_ari",
+	.requires = "res_ari",
 );

tests/test_ari_model.c

@@ -452,4 +452,9 @@ static int load_module(void)
 	return AST_MODULE_LOAD_SUCCESS;
 }
 
-AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Skeleton (sample) Test");
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Skeleton (sample) Test",
+	.support_level = AST_MODULE_SUPPORT_CORE,
+	.load = load_module,
+	.unload = unload_module,
+	.requires = "res_ari_model",
+);

tests/test_res_pjsip_scheduler.c

@@ -396,4 +396,9 @@ static int unload_module(void)
 	return 0;
 }
 
-AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "res_pjsip scheduler test module");
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "res_pjsip scheduler test module",
+	.support_level = AST_MODULE_SUPPORT_CORE,
+	.load = load_module,
+	.unload = unload_module,
+	.requires = "res_pjsip",
+);

tests/test_res_stasis.c

@@ -195,5 +195,5 @@ static int load_module(void)
 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Stasis Core testing",
 	.load = load_module,
 	.unload = unload_module,
-	.nonoptreq = "res_stasis",
+	.requires = "res_stasis",
 );

tests/test_stasis_endpoints.c

@@ -306,5 +306,5 @@ static int load_module(void)
 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Endpoint stasis-related testing",
 	.load = load_module,
 	.unload = unload_module,
-	.nonoptreq = "res_stasis_test",
+	.requires = "res_stasis_test",
 );