buildtypes: Set default for cmake build type

cmake, by default, uses CMAKE_BULD_TYPE=Debug with implies '-O0'. This
has a severe performance impact for most software. Let bee use
CMAKE_BULD_TYPE=RelWithDebInfo by default, which implies '-O2'.

For most software, the difference between '-O2' and '-O3' is
neglectable. Bee packages with special performance considerations, for
example zlib, might use -DCMAKE_BUILD_TYPE=Release in their bee file to
force '-O3'.

buildtypes/cmake.sh.in

@@ -44,6 +44,7 @@ bee_configure() {
         -DCMAKE_INSTALL_LIBDIR=${LIBDIR} \
         -DCMAKE_COLOR_MAKEFILE=OFF \
         -DCMAKE_VERBOSE_MAKEFILE=ON \
+        -DCMAKE_BUILD_TYPE=RelWithDebInfo \
         "${@}" \
         ${BEE_BUILDTYPE_CMAKE_SOURCEDIR}
 }