fix -Wunreachable-code-loop-increment

`glGetError()` may return more than one error, yet these loops never
iterated more than once. This CL fixes that, and cleans up some useless
casting.

Same fix as aosp/Ib2d3a6a95726fa954426a3644635dcf41fb571db.

Bug: 150166387, 160735304
Issue: FP4-INT#34
Test: TreeHugger
Change-Id: I7cc3a7dab0ca3a6238845b6ad291d2eb1501bc08
Merged-In: I7cc3a7dab0ca3a6238845b6ad291d2eb1501bc08
(cherry picked from commit 766aecf821028b009e90788e08307ffadc86603c)
(cherry picked from commit 1666a78e7c61ac0e45feaa482fbe487f32f42986)
1 file changed