arch/Config.in: introduce BR2_ARCH_NEEDS_GCC_AT_LEAST_15
Since we're going to introduce external toolchains that are based on
GCC 14.x, we will need them to "depends on
!BR2_ARCH_NEEDS_GCC_AT_LEAST_15", so let's introduce this symbol
first.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>