Run travis jobs in build matrix (parallel)

.travis.yml

@@ -1,8 +1,11 @@
 sudo: false
 dist: trusty
+matrix:
+  include:
+    - script: make yabar
+      compiler: gcc
       language: c
-compiler:
-    - gcc
+      env: CPPFLAGS=-DOLD_LIBCONFIG
       addons:
         apt:
           packages:
@@ -14,12 +17,12 @@ addons:
             - libxcb-icccm4-dev
             - libasound2-dev
             - libiw-dev
+    - script: make docs
+      language: generic
+      addons:
+        apt:
+          packages:
             - docbook-xml
             - asciidoc
             - xsltproc
-before_install:
-    - export CPPFLAGS=-DOLD_LIBCONFIG
-script:
-  matrix:
-      - make yabar && make install
-      - make doc && make install
+            - libxml2-utils