toolchain: set proper UTF-8 locale also for other Docker images

tools/toolchain/Dockerfile.cuda_mkl

@@ -11,6 +11,8 @@ ARG LIBINT_LMAX=5
 COPY ./install_requirements_ubuntu.sh .
 RUN ./install_requirements_ubuntu.sh
 
+ENV LANG en_US.UTF-8
+
 # Install some more Ubuntu packages.
 RUN apt-get update -qq && apt-get install -qq --no-install-recommends \
     gfortran                                                          \

tools/toolchain/Dockerfile.ubuntu_nompi

@@ -21,6 +21,7 @@ RUN export DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true && \
     git \
     less \
     libtool \
+    locales \
     make \
     nano \
     pkg-config \
@@ -39,6 +40,10 @@ RUN export DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true && \
     libhdf5-dev \
    && rm -rf /var/lib/apt/lists/*
 
+# generate a unicode-enabled locale, see https://hub.docker.com/_/ubuntu?tab=description
+RUN localedef -i C -c -f UTF-8 -A /usr/share/locale/locale.alias C.UTF-8
+ENV LANG en_US.UTF-8
+
 # Create links.
 RUN ln -sf gcc-${GCC_VERSION}      /usr/bin/gcc  && \
     ln -sf g++-${GCC_VERSION}      /usr/bin/g++  && \
@@ -62,5 +67,3 @@ RUN ./install_cp2k_toolchain.sh  \
     --with-libint=install        \
     --libint-lmax=${LIBINT_LMAX} \
     && rm -rf ./build
-
-#EOF