mb/emulation/qemu-i440fx|q35: Switch to C_ENVIRONMENT_BOOTBLOCK

Useful for testing stuff in C_ENVIRONMENT_BOOTBLOCK, like
VBOOT with separate verstage.

Changes:
* Use symbols to set up CAR and STACK
* Zero CAR area
* Move BIST failure checking to cpu folder
* Rename functions where necessary

Tested:
* qemu-2.11.2 machine pc
* qemu-2.11.2 machine q35

Test result:
* BIST error reporting is still working.
* Console starts in bootblock
* SeaBios 1.11.2 as payload is still working

Change-Id: Ibf341002c36d868b9b44c8b37381fa78ae5c4381
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/29578
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/cpu/qemu-x86/Kconfig

@@ -21,3 +21,4 @@ config CPU_QEMU_X86
 	select ARCH_RAMSTAGE_X86_32
 	select SMP
 	select UDELAY_TSC
+	select C_ENVIRONMENT_BOOTBLOCK