This diff adds new targets to install stripped versions of the targets
along with their debug symbols. The install-<component>-debug installs
such files for a single component while install-debug applies it to
all the targets.
The components installed via the install-* targets are now always
copied, even if there is no change. This minor incovenience ensures that
there is no way to split a binary twice, which would lead to empty debug
symbols.
This is not available on OSX for now as the split-debug.sh script
needs to be adapted (the strip arguments differ on OSX).
Depends on D7236.