bootstrap: relieve developpers from Gettext version mismatch issues

* .travis.yml (compile): Move the workaround from here...
* bootstrap.conf (bootstrap_epilogue): to there.

.travis.yml

@@ -50,9 +50,6 @@ jobs:
         - git submodule update --init --recursive
 
         - ./bootstrap
-        # gnulib-po/Makefile.in.in is about Gettext 0.20, which is not available in bionic.  So it will break here.  Override it.  Don't use autopoint, which sends some other files in the past.
-        - cp po/Makefile.in.in gnulib-po
-
         - ./configure --enable-gcc-warnings || { cat config.log && false; }
         - make -j2
         - make -j2 dist

bootstrap.conf

@@ -90,6 +90,13 @@ bootstrap_epilogue()
   touch src/parse-gram.[ch]
 
   perl -pi -e "s/\@PACKAGE\@/$package/g" README-release
+
+  # Bison currently uses Gettext 0.19, but the gnulib-po module
+  # imports files from more recent versions of Gettext that are not
+  # yet available widely enough (e.g., not in bionic, used by the CI).
+  # Work around this.  Don't use autopoint, which sends some other
+  # files in the past.
+  cp po/Makefile.in.in gnulib-po
 }
 
 # Keep our bootstrap script in sync with gnulib's.  If we ever need to