[gimp/gimp-2-10] po, po-plug-ins: (workaround) fixing the distcheck job in CI.

[Jehan <jehanp src gnome org>]

commit 7d9fd36cd8fe5123dfa237586552b82fdd971105
Author: Jehan <jehan girinstud io>
Date:   Sat Dec 12 16:19:24 2020 +0100

    po, po-plug-ins: (workaround) fixing the distcheck job in CI.
    
    Now the distcheck job fails with the following error:
    
    > ERROR: files left in build directory after distclean:
    > ./po/.intltool-merge-cache.lock
    > ./po-plug-ins/.intltool-merge-cache.lock
    > make[1]: *** [Makefile:1155: distcleancheck] Error 1
    
    There is definitely some change which happened on Debian packages,
    either on intltool-merge itself, or something around, because these are
    behavior breakage. We never set such `.intltool-merge-cache.lock` lock
    files ourselves, so obviously we should not be the ones to clean these.
    This is only a workaround which should be removed once upstream fixed
    the issue.
    
    (cherry picked from commit 9e4aa586f75a8255f2b49afc01115fa391081b36)

 po-plug-ins/Makefile.in.in | 6 ++++++
 po/Makefile.in.in          | 6 ++++++
 2 files changed, 12 insertions(+)
---
diff --git a/po-plug-ins/Makefile.in.in b/po-plug-ins/Makefile.in.in
index 32353654b8..360ef4be02 100644
--- a/po-plug-ins/Makefile.in.in
+++ b/po-plug-ins/Makefile.in.in
@@ -218,3 +218,9 @@ stamp-it: Makefile.in.in $(top_builddir)/config.status POTFILES.in
 # Tell versions [3.59,3.63) of GNU make not to export all variables.
 # Otherwise a system limit (for SysV at least) may be exceeded.
 .NOEXPORT:
+
+# Around December of 2020, a possible change on intltool-merge or some
+# other dependency in Debian testing broke the CI distcheck job, leaving
+# some lock files. This CLEANFILES rule should be removed once this is
+# fixed upstream.
+CLEANFILES += .intltool-merge-cache.lock
diff --git a/po/Makefile.in.in b/po/Makefile.in.in
index 31defaa86a..9a941c1c26 100644
--- a/po/Makefile.in.in
+++ b/po/Makefile.in.in
@@ -227,3 +227,9 @@ stamp-it: Makefile.in.in $(top_builddir)/config.status POTFILES.in
 # Tell versions [3.59,3.63) of GNU make not to export all variables.
 # Otherwise a system limit (for SysV at least) may be exceeded.
 .NOEXPORT:
+
+# Around December of 2020, a possible change on intltool-merge or some
+# other dependency in Debian testing broke the CI distcheck job, leaving
+# some lock files. This CLEANFILES rule should be removed once this is
+# fixed upstream.
+CLEANFILES += .intltool-merge-cache.lock