RFR(S): 8238723: yank_alloc_node must remove membar

[Nils Eliasson]

Hi,

In my patch for improving allocation expansion (8237581) there was a 
missing piece that can cause failures when disabling escape analysis.

The alloc nodes result node may have no real uses (alloc_cast() == 
NULL), but still have a membar that uses the result proj. This patch 
clean up all these other uses from the result proj.

Bug: https://bugs.openjdk.java.net/browse/JDK-8238723
Webrev: http://cr.openjdk.java.net/~neliasso/8238723/webrev.01/

Please review,

Best regards,
Nils Eliasson