CI: make the release script more flexible

ci/RELEASE.sh

@@ -15,24 +15,40 @@
 #   - pulling translations
 #   - updating the language list
 #   - switching to the right branch
+#
+# You can influence the script a little with environment variables:
+#   - BUILD_DEFAULT set to false to avoid first build with gcc
+#   - BUILD_CLANG   set to false to avoid second build with clang
+#   - BUILD_ONLY    set to true to break after building
 
 test -d .git || { echo "Not at top-level." ; exit 1 ; }
 test -d src/modules || { echo "No src/modules." ; exit 1 ; }
 
 which cmake > /dev/null 2>&1 || { echo "No cmake(1) available." ; exit 1 ; }
 
-### Build with default compiler
+test -z "$BUILD_DEFAULT" && BUILD_DEFAULT=true
+test -z "$BUILD_CLANG" && BUILD_CLANG=true
+test -z "$BUILD_ONLY" && BUILD_ONLY=false
+
+### Setup
 #
 #
 BUILDDIR=$(mktemp -d --suffix=-build --tmpdir=.)
+
+### Build with default compiler
+#
+#
+if test "x$BUILD_DEFAULT" = "xtrue" ; then
     rm -rf "$BUILDDIR"
     mkdir "$BUILDDIR" || { echo "Could not create build directory." ; exit 1 ; }
     ( cd "$BUILDDIR" && cmake .. && make -j4 ) || { echo "Could not perform test-build." ; exit 1 ; }
     ( cd "$BUILDDIR" && make test ) || { echo "Tests failed." ; exit 1 ; }
+fi
 
 ### Build with clang
 #
 #
+if test "x$BUILD_CLANG" = "xtrue" ; then
     if which clang++ > /dev/null 2>&1 ; then
         # Do build again with clang
         rm -rf "$BUILDDIR"
@@ -40,6 +56,12 @@ if which clang++ > /dev/null 2>&1 ; then
         ( cd "$BUILDDIR" && CC=clang CXX=clang++ cmake .. && make -j4 ) || { echo "Could not perform test-build." ; exit 1 ; }
         ( cd "$BUILDDIR" && make test ) || { echo "Tests failed." ; exit 1 ; }
     fi
+fi
+
+if test "x$BUILD_ONLY" = "xtrue" ; then
+    echo "Builds completed, release stopped."
+    exit 1
+fi
 
 ### Get version number for this release
 #