Patch merged into coreboot/master: Makefile.inc: Stop running git repeatedly for each build

the following patch was just integrated into master:
commit 3812597c668b795d4fc85578021e501f2a56f6b9
Author: Martin Roth 
Date:   Tue Apr 19 20:15:16 2016 -0600

Makefile.inc: Stop running git repeatedly for each build

Currently, the coreboot makefiles repeatedly run git to try to set
    the KERNELVERSION variable and to fetch the submodules.  This happens
    three times for every build.  By exporting a variable, we can catch
    this on recursive makes and not run each of these steps again.

Change-Id: I85ab867b40e80c36bd94d48510ffe3252c6cf93f
    Signed-off-by: Martin Roth 
    Reviewed-on: https://review.coreboot.org/14392
    Tested-by: build bot (Jenkins)
    Reviewed-by: Alexander Couzens

See https://review.coreboot.org/14392 for details.

-gerrit