build: workaround picky LLVM ld

```
  CXXLD libgxs_mysql_adaptor.la
ld: error: version script assignment of 'global' to symbol
'get_module' failed: symbol not defined
```

default.sym

@@ -4,9 +4,9 @@ global:
 	HOOK_*;
 	PROC_*;
 	SVC_*;
-	get_module;
-	pam_sm_authenticate;
-	pam_sm_setcred;
+	get_module*;
+	pam_sm_authenticate*;
+	pam_sm_setcred*;
 	/* Stay global so the linker can merge definitions to satisfy ODR */
 	extern "C++" {
 		std::*::_S_*;