CONFIG_TOOLCHAIN_HAS_V is not available for thedefaultarchitecture x86.
Result is shown for architecture riscv

CONFIG_TOOLCHAIN_HAS_V (not configurable)

configname: CONFIG_TOOLCHAIN_HAS_V

Linux Kernel Configuration
└─>Platform type
└─>TOOLCHAIN_HAS_V
In linux kernel since version 6.5 (release Date: 2023-08-27)  
depends
CONFIG_AS_HAS_OPTION_ARCH
CONFIG_LD_VERSIONCONFIG_23800 or CONFIG_LLD_VERSIONCONFIG_140000
CONFIG_cc-option or  NOT CONFIG_32BIT
CONFIG_cc-option or  NOT CONFIG_64BIT

is selected by
CONFIG_RISCV_ISA_V