pass branch name to docker build

docker/linux_cross-shstk/Dockerfile

@@ -1,5 +1,6 @@
 ARG DOCKER_PREFIX=wapmobil/
 ARG IMAGE_FROM
+ARG BRANCH=release
 FROM ${DOCKER_PREFIX}${IMAGE_FROM}
 
 ARG LIBS_BUILD_NUMBER=9999
@@ -8,7 +9,7 @@ ARG support_gl=1
 ENV PATH=/opt/cmake/bin:$PATH 
 
 WORKDIR /soft
-RUN git clone -b release --single-branch --depth 1 --recursive https://git.shstk.ru/SHS/shstk.git
+RUN git clone -b ${BRANCH} --single-branch --depth 1 --recursive https://git.shstk.ru/SHS/shstk.git
 
 WORKDIR /soft/shstk_build_host
 RUN cmake -G Ninja -DICU=0 -DCROSSTOOLS=1 -DBUILD_NUMBER=${LIBS_BUILD_NUMBER} ../shstk \