Merge branch 'ls/travis-stricter-linux32-builds'

32-bit Linux build on Travis CI uses stricter compilation options.

* ls/travis-stricter-linux32-builds:
  travis-ci: set DEVELOPER knob for Linux32 build

Author: gitster

.travis.yml

@@ -61,6 +61,7 @@ matrix:
         - >
           docker run
           --interactive
+          --env DEVELOPER
           --env DEFAULT_TEST_TARGET
           --env GIT_PROVE_OPTS
           --env GIT_TEST_OPTS