fix typo in xed_mbuild.py missing 'env' affecting no-encoder build.
fix typo in xed_mbuild.py missing 'env' affecting no-encoder build.

  * issue #41 on github.

Change-Id: I8710e0c64afdb7083e5aa8f68d975d1fdcf0da63
(cherry picked from commit cdc7dbbf008cccc9592c469a74a4cf8085a14d95)

intelxed/xed,intelxed/xed,intelxed/xed,intelxed/xed