test: add trivial test for syscall table and extend table tests to error paths

src/test/test-tables.c

@@ -43,6 +43,7 @@
 #include "unit-name.h"
 #include "unit.h"
 #include "util.h"
+#include "syscall-list.h"
 
 #include "test-tables.h"
 
@@ -98,5 +99,7 @@ int main(int argc, char **argv) {
         test_table(unit_load_state, UNIT_LOAD_STATE);
         test_table(unit_type, UNIT_TYPE);
 
+        _test_table("syscall", syscall_to_name, syscall_from_name, syscall_max());
+
         return EXIT_SUCCESS;
 }