LoongArch: Allow building with kcov coverage

Add ARCH_HAS_KCOV and HAVE_GCC_PLUGINS to the LoongArch Kconfig. And
also disable instrumentation of vdso.

Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
3 files changed