argument parsing refactoring, round 2

[David Bremner]

Thanks to Mark for pointing out on IRC that the previous version had problems linking the test suite helpers. That's fixed here by adding a couple stubs.

Here's the diff, roughly with the previous version (actually the first
hunk is with a slightly later version, where I fixed one bug and
introduced another).

diff --git a/notmuch-config.c b/notmuch-config.c
index 568b3dc..f2cd6a8 100644
--- a/notmuch-config.c
+++ b/notmuch-config.c
@@ -885,9 +885,9 @@ notmuch_config_command (notmuch_config_t *config, int argc, char *argv[])
 
     notmuch_process_shared_options (argv[0]);
 
-    /* skip subcommand argument */
-    argc-= opt_index+1;
-    argv+= opt_index+1;
+    /* skip at least subcommand argument */
+    argc-= opt_index;
+    argv+= opt_index;
 
     if (argc < 1) {
 	fprintf (stderr, "Error: notmuch config requires at least one argument.\n");
diff --git a/notmuch-setup.c b/notmuch-setup.c
index 5fc6e25..6a020dc 100644
--- a/notmuch-setup.c
+++ b/notmuch-setup.c
@@ -155,7 +155,7 @@ notmuch_setup_command (notmuch_config_t *config,
     if (opt_index < 0)
 	return EXIT_FAILURE;
 
-    notmuch_process_shared_options (argv[0]);
+    notmuch_process_shared_options ("setup");
 
     if (notmuch_config_is_new (config))
 	welcome_message_pre_setup ();
diff --git a/test/random-corpus.c b/test/random-corpus.c
index 790193d..6c467bb 100644
--- a/test/random-corpus.c
+++ b/test/random-corpus.c
@@ -114,6 +114,15 @@ random_utf8_string (void *ctx, size_t char_count)
     return buf;
 }
 
+/* stubs since we cannot link with notmuch.o */
+const notmuch_opt_desc_t notmuch_shared_options[] = {
+	{ 0, 0, 0, 0, 0 }
+};
+
+void
+notmuch_process_shared_options (unused (const char *dummy))
+{
+}
 
 int
 main (int argc, char **argv)