improve dd4hep cmake flags

dd4hep.spec

@@ -9,33 +9,35 @@ Source: git+https://github.com/%{github_user}/DD4hep.git?obj=%{branch}/%{tag}&ex
 BuildRequires: cmake
 Requires: root boost clhep xerces-c geant4
 
+%define cmake_fixed_args \\\
+  -DCMAKE_INSTALL_PREFIX='%{i}' \\\
+  -DBoost_NO_BOOST_CMAKE=ON \\\
+  -DDD4HEP_USE_XERCESC=ON \\\
+  -DDD4HEP_USE_PYROOT=ON \\\
+  -DCMAKE_CXX_STANDARD=17 \\\
+  -DCMAKE_BUILD_TYPE=Release \\\
+  -DCMAKE_CXX_FLAGS_RELEASE='-O2 -DNDEBUG' \\\
+  -DDD4HEP_USE_GEANT4_UNITS=ON \\\
+  -DXERCESC_ROOT_DIR=${XERCES_C_ROOT} \\\
+  -DCMAKE_PREFIX_PATH="${CLHEP_ROOT};${XERCES_C_ROOT}"
+
 %prep
 
 %setup -n %{n}-%{realversion}
 
 %build
 
 export BOOST_ROOT
-CMAKE_ARGS="-DCMAKE_INSTALL_PREFIX='%{i}' \
-      -DBoost_NO_BOOST_CMAKE=ON \
-      -DDD4HEP_USE_XERCESC=ON \
-      -DXERCESC_ROOT_DIR=${XERCES_C_ROOT} \
-      -DDD4HEP_USE_PYROOT=ON \
-      -DCMAKE_CXX_STANDARD=17 \
-      -DCMAKE_BUILD_TYPE=Release \
-      -DCMAKE_CXX_FLAGS_RELEASE="-O2 -DNDEBUG" \
-      -DDD4HEP_USE_GEANT4_UNITS=ON \
-      -DCMAKE_PREFIX_PATH=${CLHEP_ROOT};${XERCES_C_ROOT}"
 
 #Build normal Shared D4Hep without Geant4
 rm -rf ../build; mkdir ../build; cd ../build
-cmake $CMAKE_ARGS -DBUILD_SHARED_LIBS=ON ../%{n}-%{realversion}
+cmake %{cmake_fixed_args} -DBUILD_SHARED_LIBS=ON ../%{n}-%{realversion}
 make %{makeprocesses} VERBOSE=1
 make install
 
 #Building DDG4 static
 rm -rf ../build-g4; mkdir ../build-g4; cd ../build-g4
-cmake $CMAKE_ARGS -DBUILD_SHARED_LIBS=OFF -DDD4HEP_USE_GEANT4=ON ../%{n}-%{realversion}
+cmake %{cmake_fixed_args} -DBUILD_SHARED_LIBS=OFF -DDD4HEP_USE_GEANT4=ON ../%{n}-%{realversion}
 cd DDG4
 make %{makeprocesses} VERBOSE=1
 for lib in $(ls ../lib/libDDG4*.a | sed 's|.a$||'); do