VideoCommon: fix indirect texture coordinate computation in TEV.

Even if an indirect texture stage doesn't actually sample a texture, we
still need to emit the relevant math.

Fixes Issue 7092.
VideoCommon: correctly compute whether an indirect texture stage is active.

This is consistent with the implementation in PixelShaderGen.
Enables usage of GLSL textureSize on Qualcomm v66.

Qualcomm's v66 drivers have a working textureSize() function now.
Enable usage of it.
Merge pull request #344 from magumagu/tev-indirect

VideoCommon: fix indirect texture coordinate computation in TEV.
Merge pull request #345 from Sonicadvance1/Qualcomm-textureSize

Enables usage of GLSL textureSize on Qualcomm v66.
OpenGL: delete unused function parameter in TextureConverter.

(While I'm here, also mark some functions static.)
Merge pull request #339 from magumagu/opengl-unused-parameter

OpenGL: delete unused function parameter in TextureConverter.