accel/kvm: move KVM_HAVE_MCE_INJECTION define to kvm-all.c

accel/kvm: move KVM_HAVE_MCE_INJECTION define to kvm-all.c

This define is used only in accel/kvm/kvm-all.c, so we push directly the
definition there. Add more visibility to kvm_arch_on_sigbus_vcpu() to
allow removing this define from any header.

The architectures defining KVM_HAVE_MCE_INJECTION are i386, x86_64 and
aarch64.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20250325045915.994760-18-pierrick.bouvier@linaro.org>