cmake: toolchain disable -imacro deduplication

This commit introduces disabling of de-duplication for imacro.
Disabling of de-duplication allows for a space between the imacro flag
and arguments.
This allows for broader range of compiler support in future.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
1 file changed