Looks like we can use apt-get inside bitbucket-pipelines.yml.

--HG--
branch : develop

bitbucket-pipelines.yml

@@ -1,3 +1,4 @@
+image: gcc
 pipelines:
   default:
     - step:
@@ -11,6 +12,8 @@ pipelines:
             - uname -a
             - grep -i processor /proc/cpuinfo | wc -l
             - gcc --version
+            - apt-get update # required to install qt
+            - apt-get install -y qtbase5-dev libqt5svg5-dev qt5-default qttools5-dev-tools libqt5xmlpatterns5-dev libqt5core5a libqt5gui5 libqt5printsupport5 libqt5svg5 libqt5widgets5 libqt5xml5 libqt5xmlpatterns5 xpdf
             - mkdir build
             - cd build
             - qmake --version