Remove warnings-as-errors by default

Compiling C++ on various different platforms with as many out of tree
dependencies as we have is volatile at best.
In order to prevent a third party warning from ruining the build for
people who don't care about third party warnings, we remove
warnings-as-errors by default.
They are still enabled by default on CI.

build_scripts/linux/build_linux.sh

@@ -1,15 +1,30 @@
 #!/usr/bin/env bash
 set -e
+
+QMAKE_SPEC='linux-g++'
+
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 PROJECT_DIR=$SCRIPT_DIR/../../
 BUILD_DIR=$PROJECT_DIR/build/
-. $SCRIPT_DIR/configure.sh
+
+if [[ -z $USE_TIDY ]]; then
+    MAKE_COMMAND="make --jobs ${MAKE_JOBS}"
+    CLANG_TIDY=
+else
+    # Bear replaces the compile database, it does not update it.
+    # If you run 'bear make' and there is nothing to compile, you
+    # will get an empty database.
+    # Clean up the artifacts and run everything together in that case.
+    MAKE_COMMAND='bear make --jobs'
+    QMAKE_SPEC='linux-clang'
+    CLANG_TIDY="$SCRIPT_DIR/run-clang-tidy.sh"
+fi
 
 echo $MAKE_COMMAND
 mkdir -p $BUILD_DIR
 cd $BUILD_DIR
 qmake --version
-qmake -spec $QMAKE_SPEC $PROJECT_DIR $QMAKE_EXTRAS
+qmake -spec $QMAKE_SPEC $PROJECT_DIR CONFIG+=warnings_as_errors
 $MAKE_COMMAND
 $CLANG_TIDY