Fix: prefix path

Dockerfile

@@ -11,7 +11,8 @@ WORKDIR /workspace
 
 RUN echo "**** setup environment ****" && \
     export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64 && \
-    export PATH=$JAVA_HOME/bin:$PATH && \
+    export QT_INSTALL_DIR=/usr/lib/qt && \
+    export PATH=$QT_INSTALL_DIR/bin:$JAVA_HOME/bin:$PATH && \
     export QT_EVERYWHERE_URL="https://download.qt.io/archive/qt/${QT_VERSION_FAMILY}/${QT_VERSION}/single/qt-everywhere-opensource-src-${QT_VERSION}.tar.xz" && \
     export ANDROID_CLI_TOOLS_URL="https://dl.google.com/android/repository/commandlinetools-linux-8512546_latest.zip" && \
     \
@@ -36,7 +37,7 @@ RUN echo "**** setup environment ****" && \
     echo "**** configure Qt ****" && \
     mkdir build-qt && cd build-qt && \
     /workspace/qt-everywhere/configure \
-        -prefix /usr/local \
+        -prefix $QT_INSTALL_DIR \
         -opensource \
         -confirm-license \
         -release \