.travis.yml: exts is not needed for tests here

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58920 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

.travis.yml

@@ -61,7 +61,7 @@ before_script:
 
 script:
   - "make -s test TESTOPTS=--color=never"
-  - "make -s $JOBS test-all TESTOPTS='-q --color=never --job-status=normal'"
+  - "make -s $JOBS test-all -o exts TESTOPTS='-q --color=never --job-status=normal'"
   - "make -s $JOBS test-rubyspec MSPECOPT=-j"
 
 # Branch matrix.  Not all branches are Travis-ready so we limit branches here.