Using ':' as the separator in --modules breaks module specifications
like
nrfxlib:nrfxlib:C:/Users/Carles/src/ncs/nrfxlib
The ':' in 'C:' gets seen as a separator.
Use ',' instead, which is unlikely to appear in paths (at least in
--modules). Treat a doubled ',,' as a literal ','.
Another option would be ';', but it clashes with how CMake represents
lists, which is awkward.
Also make quoting of arguments with spaces more robust by passing
VERBATIM to add_custom_target().
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
f570f19bef