ResizablePMCArray doesn't respond to the defined_keyed() VTABLE via the extend_vtable API

[dukeleto]

t/src/extend_vtable.t .. 
1..90
ok 1 - Parrot_PMC_exists_keyed_int
ok 2 - Parrot_PMC_exists_keyed
not ok 3 - Parrot_PMC_defined_keyed

#   Failed test 'Parrot_PMC_defined_keyed'
#   at t/src/extend_vtable.t line 170.
#          got: 'Failed!
# Exception is: type 36 severity 2 message 'defined_keyed() not implemented in class 'ResizablePMCArray''
# '
#     expected: '0
# Done!
# '
# './t/src/extend_vtable_3' failed with exit code 0

[dukeleto]

Test can be viewed here:

 https://github.com/parrot/parrot/commit/e25401439a