password dialog: avoid compiler warnings

'pwd_type' should be either MAIN_ARCHIVE or SECOND_ARCHIVE; so just assert in
the last 'else {}'. This should make sure that the compiler understands that the
code won't keep on at that point, and will skip warning about 'file' and
'old_password' being used uninitialized.

   dlg-ask-password.c: In function ‘dlg_ask_password__common’:
   dlg-ask-password.c:135:5: warning: ‘old_password’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (old_password != NULL) {
        ^
   dlg-ask-password.c:129:11: warning: ‘file’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     filename = _g_file_get_display_basename (file);
              ^

https://bugzilla.gnome.org/show_bug.cgi?id=708839
ace: avoid compiler warnings

Skip compiler warnings about 'fields' or 'field_name' being used uninitialized.

  fr-command-ace.c: In function ‘process_line’:
  fr-command-ace.c:135:20: warning: ‘field_name’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    if (field_name[0] != '/') {
                      ^
  fr-command-ace.c:122:40: warning: ‘fields’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    if ((fields == NULL) || (fields[0] == NULL) || (g_strv_length (fields) < 5))
                                       ^

https://bugzilla.gnome.org/show_bug.cgi?id=708839
cfile: avoid compiler warning

If mime type is unhandled, warning and return. Otherwise 'compressed_filename'
will be used even if uninitialized:

  fr-command-cfile.c: In function ‘fr_command_cfile_add’:
  fr-command-cfile.c:311:9: warning: ‘compressed_filename’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    g_free (compressed_filename);
           ^

https://bugzilla.gnome.org/show_bug.cgi?id=708839
test-server: reorganize the flags to decide what to run in the tester

And also make 'fileroller_getsupportedtypes_ready_cb()' be included in
compilation only when needed, to avoid compiler warnings:

   test-server.c:30:1: warning: ‘fileroller_getsupportedtypes_ready_cb’ defined but not used [-Wunused-function]
    fileroller_getsupportedtypes_ready_cb (GObject      *source_object,
    ^

https://bugzilla.gnome.org/show_bug.cgi?id=708839
archive: fix compiler warnings

Compiler doesn't seem to understand that 'ra' is only used after checking that
'load_data->error == NULL'. Just silence the error initializing the variables.

   fr-archive-libarchive.c: In function ‘save_archive_thread’:
   fr-archive-libarchive.c:1417:40: warning: ‘ra’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     if ((load_data->error == NULL) && (ra != ARCHIVE_EOF))

https://bugzilla.gnome.org/show_bug.cgi?id=708839