Implement: dup_{d_d[], s_s[], h_h[], b_b[]}, ext


git-svn-id: svn://svn.valgrind.org/vex/trunk@2880 8f6e269a-dfd6-0310-a8e1-e2731360e62c
Increase the number of vector registers available for allocation from
3 to 5.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2881 8f6e269a-dfd6-0310-a8e1-e2731360e62c