Simplify path allocation, clean up resources correctly

Simplify path id allocation in NVPR backend. Instead of using
an AVL tree of path id ranges for the first 65535 ids, use just
a simple stategy of overallocation and "bump index".

Fixes the bug where previously overallocated ids were not deleted.

The advantage is that the implementation is simple and all allocations
go through overallocation, not just the first 65535 of the 1-range
allocations.

Removes the logic where paths were cleared with setting path data to
null instead of deleting the whole path. Now deleted paths are just
deleted normally. These operations should have equivalent performance on
command buffer. Deleting the path should enable the driver to do more
maintainance.

Removes the GLNameAllocator, as it was only used for paths. In order for
it to be used for other IDs, it probably would need to be re-written to
support cleanup and arbitrary ranges. Also, the interface would probably
need to be changed to not requiring the block to be allocated before it
could be managed by the structure.
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Review URL: https://codereview.chromium.org/1150243003
7 files changed