arch/x86: Include acpi_s3.c support in postcar stage

This patch ensures acpi APIs are available for postcar
stage.

Change-Id: Ia0f83cd4886ba7a16286dbbeb3257ede014ee3c7
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/21626
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/arch/x86/Makefile.inc b/src/arch/x86/Makefile.inc
index 04e679f..813e01b 100644
--- a/src/arch/x86/Makefile.inc
+++ b/src/arch/x86/Makefile.inc
@@ -278,6 +278,7 @@
 $(eval $(call create_class_compiler,postcar,x86_32))
 postcar-generic-ccopts += -D__POSTCAR__
 
+postcar-$(CONFIG_HAVE_ACPI_RESUME) += acpi_s3.c
 postcar-y += boot.c
 postcar-y += cbfs_and_run.c
 postcar-y += cbmem.c
diff --git a/src/arch/x86/acpi_s3.c b/src/arch/x86/acpi_s3.c
index 0a17ead..90f2c4e 100644
--- a/src/arch/x86/acpi_s3.c
+++ b/src/arch/x86/acpi_s3.c
@@ -25,7 +25,7 @@
 #include <rules.h>
 #include <symbols.h>
 
-#if ENV_RAMSTAGE
+#if ENV_RAMSTAGE || ENV_POSTCAR
 
 /* This is filled with acpi_is_wakeup() call early in ramstage. */
 static int acpi_slp_type = -1;