Merge branch 'ls/travis-enable-httpd-tests' into maint

Allow http daemon tests in Travis CI tests.

* ls/travis-enable-httpd-tests:
  travis-ci: enable web server tests t55xx on Linux

Author: gitster

.travis.yml

@@ -19,6 +19,7 @@ addons:
     packages:
     - language-pack-is
     - git-svn
+    - apache2
 
 env:
   global:
@@ -31,6 +32,7 @@ env:
     - DEFAULT_TEST_TARGET=prove
     - GIT_PROVE_OPTS="--timer --jobs 3 --state=failed,slow,save"
     - GIT_TEST_OPTS="--verbose --tee"
+    - GIT_TEST_HTTPD=true
     - GIT_TEST_CLONE_2GB=YesPlease
     # t9810 occasionally fails on Travis CI OS X
     # t9816 occasionally fails with "TAP out of sequence errors" on Travis CI OS X