Fix integer overflow when framebuffers are extremely high resolution resulting in INT_MAX texture bias (#393)

DRTVWR-559 Revert skies to be very close to release and disable tone mapping when probe ambiance is zero.

Hack for desaturating legacy materials has been removed for performance and quality reasons.

Adds a new setting for auto adjusting legacy skies.  This is the PBR "opt out" button.  If disabled, legacy skies will disable tonemapping, automatic probe ambiance, and HDR/exposure.  If enabled, legacy skies will behave as if probe ambiance and HDR scale are 1.0, and ambient will be cut in half.  

HDR scale will act as a sky brightener, but will automatically adjust dynamic exposure so the sky will be properly exposed.  If you want relatively even exposure all the time, set HDR Scale to 1.0.  If you want a high range of exposures between indoor/dark areas and outdoor/bright areas, increase HDR Scale.

Also tuned up SSAO (thanks Rye!).

Reviewed with Brad.

DRTVWR-559
DRTVWR-583

* Add a binary cache for compiled shaders using glProgramBinary

* Add additional sanity checking to shader binary save and load, hook up cache clear and menu option

* Fix default init of shader cache data struct and clear gl errors before glGetError calls

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Co-authored-by: RunitaiLinden <davep@lindenlab.com>

SL-19709 Fix for fullbright shiny not factoring out exposure and flickering fullbright alpha.  Incidental decruft.

DRTVWR-583

Rather than continuing to propagate try/catch (Closed)
(aka LLThreadSafeQueueInterrupt) constructs through the code base, make
WorkQueueBase::post() return bool indicating success (i.e. ! isClosed()).
This obviates postIfOpen(), which no one was using anyway.

In effect, postIfOpen() is renamed post(), bypassing the exception when
isClosed().

Review existing try/catch blocks of that sort, changing to test for post()
returning false.

DRTVWR-559 Optimization pass, make it so profileAvatar can read back GPU timer without a frame stall.

DRTVWR-559 Add "No Post" mode and refactor "Scene Gamma" into "Brightness" for adjusting legacy gamma when probe ambiance is 0 and dynamic exposure when probe ambiance is not zero.

DRTVWR-583

SL-19564 Rebalance exposure and sky.  Hack legacy diffuse map saturation and brightness to allow ACES Hill all the time.

Need to fix up bloom.

DRTVWR-559
SL-19524
SL-19513

SL-19538 Followup -- scrub all possible sources of NaNs, make dynamic exposure controls not persist, limit exposure range, and do a debug gl pass.

* SL-19538 Followup -- fix for dynamic exposure having large gaps in its luminance sampling.

* SL-19538 Followup -- review feedback changes.

SL-19538 Followup -- tune exposure parameters and clamp local light ambiance.  Make render targets 16F and scrube NaNs (thanks Rye).  Update midday. (#154)

* SL-19331: Have media updates on the LLImageGL thread even when texture updates are on the main thread. Add config.

Off-thread media updates seem work best performance-wise when using glTexImage2D, not sub_image_lines. Otherwise, there are lots of main thread stalls.

* SL-19331: Bump featuretable

* SL-19331: Cleanup, annotate comment

* SL-19538 Remove hacky ambiance scale and take the mittens off probe ambiance values.  Fix for sky brightening being done in sRGB space.

SL-19513

This reverts commit 084ef517.