Compute GPU projection matrix from camera's projection matrix.

In Unity, projection matrices follow OpenGL convention. However on some platforms they have to be transformed a bit to match the native API requirements. Use this function to calculate how the final projection matrix will be like. The value will match what comes as UNITY_MATRIX_P matrix in a shader.

The renderIntoTexture value should be set to true if you intend to render into a RenderTexture with this projection matrix. On some platforms it affects how the final matrix will look like.