unused arguments in tests

[reedjc]

This is trivial and maybe something to do discuss. But -Wall (or -Wunused-parameter) fails for some tests like:

t/test-rdata_to_str.c: In function ‘main’:
t/test-rdata_to_str.c:269:15: error: unused parameter ‘argc’ [-Werror=unused-parameter]
 int main (int argc, char **argv) {
               ^
t/test-rdata_to_str.c:269:28: error: unused parameter ‘argv’ [-Werror=unused-parameter]
 int main (int argc, char **argv) {

Trivial to fix in a few files:

-int main (int argc, char **argv) {
+int main(void) {

[reedjc]

This is fixed. Now in master and 0.10.0