Removing event hooks can AIOOB

[enebo]

Originally from PR #2604 ... I am solving this differently than the original PR. In addition to the original reporters problem of seeing us walk off the edge of the newHooks array this method was also broken because it would not work if the contained hook was not contained in the list.

Testing a fix for this as I write the description. Tip of the hat to @gsamokovarov for the simple reproduction:

require 'coverage'
Coverage.start

set_trace_func proc { |*args| p args }

[enebo]

Cheryy-picked this back to jruby-1_7 as well.

[gsamokovarov]

Thanks for fixing this!