Support r_srgb even without hardware support. Also tweak default autoexposure/tonemap settings to look good on both r_srgb 0 and 1.

code/rend2/tr_backend.c

@@ -1747,7 +1747,7 @@ const void *RB_PostProcess(const void *data)
 			autoExposure = r_autoExposure->integer || r_forceAutoExposure->integer;
 			RB_ToneMap(srcFbo, autoExposure);
 		}
-		else if (!glRefConfig.framebuffer_srgb && r_cameraExposure->value == 0.0f)
+		else if (r_cameraExposure->value == 0.0f)
 		{
 			FBO_FastBlit(srcFbo, NULL, tr.screenScratchFbo, NULL, GL_COLOR_BUFFER_BIT, GL_NEAREST);
 		}