SL-19966 Reverted "SL-18721: Faster viewer shutdown time since performance improvements can lead to perceived inventory loss due to cache corruption"

This reverts commit cf692c40.

from U32*.

(cherry picked from commit eb0516b9940f200b32349d611f38f1ccee48005d)

Pass llssize instead of S32.

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.

Fix LLThreadSafeQueueInterrupt in WorkQueueBase::postTo during shutdown by catching and returning false

Newer C++ compilers have different semantics around LLSDArray's special copy
constructor, which was essential to proper LLSD nesting. In short, we can no
longer trust LLSDArray to behave correctly. Now that we have variadic
functions, get rid of LLSDArray and replace every reference with llsd::array().

The trouble with debugLoggingEnabled() is that it locked mutexes and searched
maps every time that call was reached. LL_DEBUGS() has the same functionality
(albeit with idiosyncratic syntax) but performs expensive lookups only once
per session, caching the result in a local static variable.

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

SL-18721: Faster viewer shutdown time since performance improvements can lead to perceived inventory loss due to cache corruption

DRTVWR-559 Return to MD5 for LLUUID operations.  Existing LLUUID API implementations must not change, but may add "fast" variants where appropriate in the future.

per Leviathan code review.

instead of having specific binary, ternary and quaternary overloads.

The num_periods arguments have all been changed to size_t, but the default
argument values were still coded as S32_MAX. Change to
std::numeric_limits<size_t>::max().

Not only do the local typedefs make the code less readable, they also rely on
assumptions about the implementation. The standard types are guaranteed by the
C++ library implementation.