LLThread::currentID() used to return a U32, a distinct unsigned value
incremented by explicitly constructing LLThread or by calling LLThread::
registerThreadID() early in a thread launched by other means. The latter
imposed an unobvious requirement on new code based on std::thread. Using
std::thread::id instead delegates to the compiler/library the problem of
distinguishing threads launched by any means.

Change lots of explicit U32 declarations. Introduce LLThread::id_t typedef to
avoid having to run around fixing uses again if we later revisit this decision.

LLMutex, which stores an LLThread::id_t, wants a distinguished value meaning
NO_THREAD, and had an enum with that name. But as std::thread::id promises
that the default-constructed value is distinct from every valid value,
NO_THREAD becomes unnecessary and goes away.

Because LLMutex now stores LLThread::id_t instead of U32, make llmutex.h
#include "llthread.h" instead of the other way around. This makes LLMutex an
incomplete type within llthread.h, so move LLThread::lockData() and
unlockData() to the .cpp file. Similarly, remove llrefcount.h's #include
"llmutex.h" to break circularity; instead forward-declare LLMutex.

It turns out that a number of source files assumed that #include "llthread.h"
would get the definition for LLMutex. Sprinkle #include "llmutex.h" as needed.

In the SAFE_SSL code in llcorehttp/httpcommon.cpp, there's an ssl_thread_id()
callback that returns an unsigned long to the SSL library. When LLThread::
currentID() was U32, we could simply return that. But std::thread::id is very
deliberately opaque, and can't be reinterpret_cast to unsigned long.
Fortunately it can be hashed because std::hash is specialized with that type.

Brought back the changes from @andreyk for improved mouse scroll wheel performance (previously 8e228364f324)

Pull in CEF 75.0.1+gb5e74dd+chromium-75.0.3770.80 and Dullahan 1.2.x along with some minor compatibility changes

Changes from @andreyk for improved mouse scroll wheel performance and pull in new Dullahan with CEF 74.1.19_gb62bacf_chromium-74.0.3729.157

SL-10811 - [Render][OSX] Google’s search results page is not fully displayed in the Media Browser if HiDPI is enabled.
SL-10813 - [Render][OSX] HiDPI browser has black bars on the sides.
Fixed.

MAINT-8325 Fixed The Save Local dialog disconnects the viewer if you do not choose the save directory files within the first minute

libatmosphere integrated in indra/llrender/llatmosphere.cpp

Still working on runtime shaders to use libatmosphere precomputed atmospherics textures

Fixes for: MAINT-8244 Text in CEF cannot be selected with the mouse. MAINT-8245 Expose CEF log file and logging severity to viewer and MAINT-8246 Expose the CEF remote debugging system to the viewer

Fixes for 'MAINT-8196 Remove LLPluginCookieStore from the viewer' and 'MAINT-8194 Remove per-frame calls to updateJavascriptObject()'

Pull in Dullahan 1.1.930 with improved fix for maint-8095 (target='_blank' links) as well as an improvement for maint-8100 (no error message for invalid hostname / url)

Remove the scary 32bit exception handler that patches kernel32.dll since it was (a) scary, (b) didn't work on 64 bit and (c) likely the cause of a lot of anti-virus false positives

The present CMake logic wants to pass FIXED:NO to the linker for 64-bit
builds, which on the face of it seems like a Good Thing: it permits code to be
relocated in memory, preventing collisions if two libraries happen to want to
load into overlapping address ranges.

However the way it's being specified is wrong and harmful. Passing /FIXED:NO
to the compiler command line engages /FI (Forced Include!) of a nonexistent
file XED:NO -- producing lots of baffling fatal compile errors.

Thanks Callum for diagnosing this!

autobuild 1.1 now supports expanding $variables within a config file --
support that was explicitly added to address this very problem. So now the
windows platform in autobuild.xml uses $AUTOBUILD_ADDRSIZE,
$AUTOBUILD_WIN_VSPLATFORM and $AUTOBUILD_WIN_CMAKE_GEN, which should handle
most of the deltas between the windows platform and windows64.

This permits removing the windows64 platform definition from autobuild.xml.

The one remaining delta between the windows64 and windows platform definitions
was -DLL_64BIT_BUILD=TRUE. But we can handle that instead by checking
ADDRESS_SIZE. Change all existing references to WORD_SIZE to ADDRESS_SIZE
instead, and set ADDRESS_SIZE to $AUTOBUILD_ADDRSIZE. Change the one existing
LL_64BIT_BUILD reference to test (ADDRESS_SIZE EQUAL 64) instead.

Update SetCookie code for new LLCEFLib API and add support for shoing/hising developer console (Inspector)