po: Remove virt-v2v related dependency from POTFILES-ml.

Causes this error if you compile libguestfs 1.42.0 from the tarball
without invoking the generator:

make[4]: *** No rule to make target '../common/mlv2v/uefi.ml', needed by 'libguestfs.pot'.  Stop.

Makefile.am

@@ -345,6 +345,7 @@ po/POTFILES-ml: configure.ac
 	cd $(srcdir); \
 	find builder common/ml* customize dib get-kernel resize sparsify sysprep -name '*.ml' | \
 	grep -v '^builder/templates/' | \
+	grep -v '^common/mlv2v/' | \
 	grep -v -E '.*_tests\.ml$$' | \
 	LC_ALL=C sort > $@-t
 	mv $@-t $@

po/POTFILES-ml

@@ -41,7 +41,6 @@ common/mltools/urandom.ml
 common/mltools/xpath_helpers.ml
 common/mlutils/c_utils.ml
 common/mlutils/unix_utils.ml
-common/mlv2v/uefi.ml
 common/mlvisit/visit.ml
 common/mlxml/xml.ml
 customize/append_line.ml