Opengl water test removal

Apparently HWR_Subsector still has some "test" for sectors with a tag higher than 32767 (wut), where a plane displaying F_WATER1 (or WATER0) is supposed to display at a height determined by the tag.

...however, it crashes when I try to make it work in a test map. After removing the test from the code and testing the map doesn't crash anymore. Nothing more needs to be said, just kill it already.