perf-test: add memory test for reply

Looking at the code for notmuch-reply, there seems to be several gmime
related memory leaks. This test is supposed to help eliminate those.

performance-test/M04-reply.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+test_description='search'
+
+. ./perf-test-lib.sh || exit 1
+
+memory_start
+
+for id in $(notmuch search --output=messages '*' | shuf -n 5); do
+    memory_run "reply $id" "notmuch reply \"$id\" 1>/dev/null"
+    memory_run "reply --format=json $id" "notmuch reply --format=json \"$id\" 1>/dev/null"
+    memory_run "reply --format=sexp $id" "notmuch reply --format=sexp \"$id\" 1>/dev/null"
+done
+
+memory_done