compiler.h: add __weak macro

Instead of writing out '__attribute__((weak))' use a shorter form.

Change-Id: If418a1d55052780077febd2d8f2089021f414b91
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/25767
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Justin TerAvest <teravest@chromium.org>
diff --git a/src/drivers/intel/fsp1_1/raminit.c b/src/drivers/intel/fsp1_1/raminit.c
index 2bdac0a..e5714ae 100644
--- a/src/drivers/intel/fsp1_1/raminit.c
+++ b/src/drivers/intel/fsp1_1/raminit.c
@@ -15,6 +15,7 @@
 
 #include <arch/acpi.h>
 #include <cbmem.h>
+#include <compiler.h>
 #include <console/console.h>
 #include <fsp/memmap.h>
 #include <fsp/romstage.h>
@@ -296,7 +297,7 @@
 }
 
 /* Initialize the UPD parameters for MemoryInit */
-__attribute__((weak)) void mainboard_memory_init_params(
+__weak void mainboard_memory_init_params(
 	struct romstage_params *params,
 	MEMORY_INIT_UPD *upd_ptr)
 {
@@ -304,7 +305,7 @@
 }
 
 /* Display the UPD parameters for MemoryInit */
-__attribute__((weak)) void soc_display_memory_init_params(
+__weak void soc_display_memory_init_params(
 	const MEMORY_INIT_UPD *old, MEMORY_INIT_UPD *new)
 {
 	printk(BIOS_SPEW, "UPD values for MemoryInit:\n");
@@ -312,7 +313,7 @@
 }
 
 /* Initialize the UPD parameters for MemoryInit */
-__attribute__((weak)) void soc_memory_init_params(
+__weak void soc_memory_init_params(
 	struct romstage_params *params,
 	MEMORY_INIT_UPD *upd)
 {