Add tests for the phase 3 ISA 2.07 code patch

This patch adds testcases to an existing testcase
source file to test the new instructions which were
added to VEX support in the phase 3 ISA 2.07 code patch.
The patch also makes a small change to memcheck's
vbit tester code to allow successful execution.

Signed-off-by: Maynard Johnson <maynardj@us.ibm.com>        

Bugzilla 324894.   Corresponding VEX commit 2779

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13594 a5019735-40e9-0310-863c-91ae7b9d1cf9