builder: Don't try to translate make-template.ml.

It fails with:

  File "../builder/templates/make-template.ml", line 1, characters 0-1:
  Parse error: [a_LIDENT] expected after "#" (in [implem])
  End_of_file
  An error occurs while processing.

In any case this doesn't matter because this file should not be
translated.

Fixes commit a1ea9a2599.

Makefile.am

@@ -327,6 +327,7 @@ po/POTFILES-ml: configure.ac
 	rm -f $@ $@-t
 	cd $(srcdir); \
 	find builder customize dib get-kernel mllib resize sparsify sysprep v2v -name '*.ml' | \
+	grep -v '^builder/templates/' | \
 	LC_ALL=C sort > $@-t
 	mv $@-t $@
 

po/POTFILES-ml

@@ -13,7 +13,6 @@ builder/setlocale.ml
 builder/sigchecker.ml
 builder/simplestreams_parser.ml
 builder/sources.ml
-builder/templates/make-template.ml
 builder/utils.ml
 builder/yajl.ml
 builder/yajl_tests.ml