treewide: remove unnecessary inclusion of gettext.h

Looking at things from the opposite angle of the last patch, we had a
few files that were including gettext.h and perhaps needed it at some
point in history, but no longer require it.  Remove the include.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/helper/test-progress.c

@@ -19,7 +19,6 @@
  */
 #define GIT_TEST_PROGRESS_ONLY
 #include "test-tool.h"
-#include "gettext.h"
 #include "parse-options.h"
 #include "progress.h"
 #include "strbuf.h"