Add crossystem arch (reports x86 or arm, depending on platform)

Change-Id: I857ead5b108d42195145cdbc5cdafa817f3416b4

R=reinauer@chromium.org
BUG=chrome-os-partner:3023
TEST=crossystem arch

(reports 'x86' on x86 platform, 'arm' on ARM platform)

Review URL: http://codereview.chromium.org/6813054
diff --git a/utility/crossystem_main.c b/utility/crossystem_main.c
index 3163438..133ab00 100644
--- a/utility/crossystem_main.c
+++ b/utility/crossystem_main.c
@@ -47,6 +47,7 @@
   {"tpm_fwver", 0, "Firmware version stored in TPM", "0x%08x"},
   {"tpm_kernver", 0, "Kernel version stored in TPM", "0x%08x"},
   /* Read-only strings */
+  {"arch", IS_STRING, "Platform architecture"},
   {"hwid", IS_STRING, "Hardware ID"},
   {"fwid", IS_STRING, "Active firmware ID"},
   {"ro_fwid", IS_STRING, "Read-only firmware ID"},