Blender Git Loki

Revert "Make 'incompatible pointer type' gcc warning an error by default."

This reverts commit b5bd39b5182590fd4d5ddb24d7b7bdbe714d57bf.

This is problematic because it means minor differences in system headers can cause errors
(glew in this case errored for me both with system and Blender's bundled version).

Developers can enable -Werror=* locally for warnings that aren't reliable across different systems.