i18n: git-am core say messages

Make the core git-am messages that use say() translatable. These are
visible on almost every git am invocation.

There are tests that depend on the "Applying" output that need to be
changed to use the test_i18* functions along with this translation.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-am.sh

@@ -742,7 +742,7 @@ To restore the original branch and stop patching run \"\$cmdline --abort\"."; ec
 		stop_here $this
 	fi
 
-	say "Applying: $FIRSTLINE"
+	say "$(eval_gettext "Applying: \$FIRSTLINE")"
 
 	case "$resolved" in
 	'')
@@ -787,7 +787,7 @@ did you forget to use 'git add'?"; echo
 		    # Applying the patch to an earlier tree and merging the
 		    # result may have produced the same tree as ours.
 		    git diff-index --quiet --cached HEAD -- && {
-			say No changes -- Patch already applied.
+			say "$(gettext "No changes -- Patch already applied.")"
 			go_next
 			continue
 		    }
@@ -813,7 +813,7 @@ did you forget to use 'git add'?"; echo
 			GIT_AUTHOR_DATE=
 		fi
 		parent=$(git rev-parse --verify -q HEAD) ||
-		say >&2 "applying to an empty history"
+		say >&2 "$(gettext "applying to an empty history")"
 
 		if test -n "$committer_date_is_author_date"
 		then

t/t4150-am.sh

@@ -465,7 +465,7 @@ test_expect_success 'am newline in subject' '
 	test_tick &&
 	sed -e "s/second/second \\\n foo/" patch1 >patchnl &&
 	git am <patchnl >output.out 2>&1 &&
-	grep "^Applying: second \\\n foo$" output.out
+	test_i18ngrep "^Applying: second \\\n foo$" output.out
 '
 
 test_expect_success 'am -q is quiet' '

t/t4151-am-abort.sh

@@ -45,8 +45,9 @@ do
 
 	test_expect_success "am$with3 --skip continue after failed am$with3" '
 		test_must_fail git am$with3 --skip >output &&
-		test "$(grep "^Applying" output)" = "Applying: 6" &&
-		test_cmp file-2-expect file-2 &&
+		test_i18ngrep "^Applying" output >output.applying &&
+		test_i18ngrep "^Applying: 6$" output.applying &&
+		test_i18ncmp file-2-expect file-2 &&
 		test ! -f .git/MERGE_RR
 	'