Adapt to changes in C++ dependencies

Change-Id: Id8525bb8fe46854e4b1f7cbabff623e267bdda9c
Depends-on: https://cesnet-gerrit-public/c/CzechLight/dependencies/+/3972
Depends-on: https://cesnet-gerrit-czechlight/c/CzechLight/dependencies/+/3972
Depends-on: https://gerrit.cesnet.cz/c/CzechLight/dependencies/+/3972
Depends-on: https://gerrit.cesnet.cz/c/CzechLight/dependencies/+/3971
diff --git a/ci/build.sh b/ci/build.sh
index 5cc60ab..2631003 100755
--- a/ci/build.sh
+++ b/ci/build.sh
@@ -19,13 +19,6 @@
     export CC=clang
     export CXX=clang++
     export LD=clang
-    export CXXFLAGS="-stdlib=libc++"
-    # spdlog passes std::string instances, and it's built against GCC's libstdc++ on the CI
-    sed -i \
-        -e 's/spdlog::spdlog/spdlog::spdlog_header_only/' \
-        -e '/find_package(spdlog/ a add_definitions(-DFMT_HEADER_ONLY)' \
-        -e 's/fmt::fmt/fmt::fmt-header-only/' \
-        ${ZUUL_PROJECT_SRC_DIR}/CMakeLists.txt
 fi
 
 if [[ $ZUUL_JOB_NAME =~ .*-ubsan ]]; then