build_helper_configs: Add config_rse_build_only for TC4+ARMCLANG

Create a config_rse_build_only group for RSE-specific builds only.
This is to introduce TC4 build for ArmClang along with
RSE_SUPPORT_ROM_LIB_RELOCATION set to OFF

Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
Change-Id: Icd0e8a41bf6fef56dcfdc3fd299b286662881cb9
1 file changed