propagate some path variables
propagate some path variables

If these are overridden on the command line, pass them along to
the sub-makes.

Change-Id: I531ccb5d2f5e4be8e99d4892cdcfffffc1ad9877
Signed-off-by: Andrew Boie <aab045b28152628be6af0e556050d0381fd0a34d@intel.com>

rhinstaller/shim,CyanogenMod/android_external_uefi_shim,CyanogenMod/android_external_uefi_shim,rhinstaller/shim,android-ia/platform_external_uefi_shim,CyanogenMod/android_external_uefi_shim,rhinstaller/shim,android-ia/platform_external_uefi_shim,android-ia/platform_external_uefi_shim