Update Dockerfile

docker/build_env/gpu/centos7/Dockerfile

@@ -2,7 +2,7 @@ FROM nvidia/cuda:10.1-devel-centos7
 
 ENV NVIDIA_DRIVER_CAPABILITIES compute,utility
 
-RUN yum install -y epel-release centos-release-scl-rh && yum install -y wget curl && \
+RUN yum install -y epel-release centos-release-scl-rh && yum install -y wget curl which && \
     wget -qO- "https://cmake.org/files/v3.14/cmake-3.14.3-Linux-x86_64.tar.gz" | tar --strip-components=1 -xz -C /usr/local && \
     yum install -y ccache make automake git python3-pip libcurl-devel python3-devel boost-static mysql-devel \
     devtoolset-7-gcc devtoolset-7-gcc-c++ devtoolset-7-gcc-gfortran llvm-toolset-7.0-clang llvm-toolset-7.0-clang-tools-extra lcov \