This ensures that the compiler does not move it away from
the "env = env1;" assignment.  Fixes a miscompilation
on gcc 4.4, reported by Jay Foad.

Cc: <jay.foad@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>