Fix Windows build by using Ninja

Author: agateau

ci/build-app

@@ -18,7 +18,11 @@ BUILD_CMD="cmake --build . --config $BUILD_TYPE"
 echo_title Configuring
 mkdir $BUILD_DIR
 cd $BUILD_DIR
-cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_INSTALL_PREFIX=$INSTALL_DIR $SRC_DIR
+cmake \
+    -DCMAKE_BUILD_TYPE=$BUILD_TYPE \
+    -DCMAKE_INSTALL_PREFIX=$INSTALL_DIR \
+    -G Ninja \
+    $SRC_DIR
 
 echo_title Updating translations
 $BUILD_CMD --target lupdate

ci/lib/common-dependencies.sh

@@ -57,6 +57,7 @@ install_ecm() {
             -DBUILD_MAN_DOCS=OFF \
             -DBUILD_QTHELP_DOCS=OFF \
             -DBUILD_TESTING=OFF \
+            -G Ninja \
             ..
         cmake --build .
         cmake --build . --target install