If `cpp_debugstl` is enabled in the build configuration, then
libstdc++ will try to use `==` on operators in certain cases
to carry out extra checks. This leads to build failures because
`StringSplitter::iterator` has no `operator==`.
Implement `operator==`, and express `operator!=` in terms of it.
Signed-off-by: Barnabás Pőcze <pobrn@protonmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>