fix: Update pg_amqp.c

[kumy]

Fixes #41
Should fix such errors

src/pg_amqp.c:140:21: error: parameter 'broker_id' was not declared, defaults to 'int'; ISO C99 and later do not support implicit int [-Wimplicit-int]
  140 | local_amqp_get_a_bs(broker_id) {
      |                     ^
src/pg_amqp.c:140:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  140 | local_amqp_get_a_bs(broker_id) {
      | ^
src/pg_amqp.c:152:19: error: parameter 'broker_id' was not declared, defaults to 'int'; ISO C99 and later do not support implicit int [-Wimplicit-int]
  152 | local_amqp_get_bs(broker_id) {
      |                   ^
src/pg_amqp.c:152:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  152 | local_amqp_get_bs(broker_id) {
      | ^
src/pg_amqp.c:239:23: error: parameter 'broker_id' was not declared, defaults to 'int'; ISO C99 and later do not support implicit int [-Wimplicit-int]
  239 | local_amqp_disconnect(broker_id) {
      |                       ^
src/pg_amqp.c:239:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  239 | local_amqp_disconnect(broker_id) {
      | ^
4 warnings and 3 errors generated.

[bcb]

This is needed, can we merge?

Fixes errors reported in #41, #44 and #45