Remvoe -D that had been passed in front of each entry of add_compile_definitions, this lead to '-D-D<value>'

Rework cmake, the original plan was to maybe be able to use conan targets with the same name (that's why 3ps had names like apr::apr),
but it's safer and saner to put the LL 3ps under the ll:: prefix.
This also allows means it is possible to get rid of that bad "if( TRAGET ...) return() endif()" pattern and rather use include_guard().

Fix warning supression for Linux/OSX, this was broken after the first round of cmake changes on Windows.
-Wno-unused-but-set-variable/-Wno-unused-variable moved from just Linux to also OSX (clang) as there's a lot of those
in the code where newer xcode complains. Fixing all those places is going beyond the scope of modernizing cmake.

this everythig was over the place how it was set, worse even with wrong
functions like:
- add_definitions( /arch:SSE2 )
- add_definitions(/WX)
Those are each options to cl, not definitons.

Change projects to cmake targetsto get rid of havig to hardcore
include directories and link libraries in consumer projects.

This reverts commit 203ea3a7, reversing
changes made to 8e3f0778.

# Conflicts:
#	indra/newview/llmachineid.cpp

(cherry picked from commit 28deadab)

This reverts commit 28deadab.

Going there implies other changes, will take up on another branch.

This reverts commit a106d6cf.

This set of changes reverts the merge with master (git revert c83e740e) and results in a version of the DRTVWR-519 that matches what was presemt before it was deployed as a release viewer *plus* 3 small fixes from Maxim (See commits).  This branch can now be used for additional fixes before eventually being used to release D-519 as normal

This reverts commit e61f485a, reversing
changes made to 00c47d07.

Effective rename of DRTVWR-506-simple since there is no way to rename a branch. Cloned canonical viewer into DRTVWR-519, copied over the files that changed from DRTVWR-506-simple and pushed back.  Once I am satisfied everything is correct, DRTVWR-506-simple will be removed

Small change to CMake options to only enable the PreferredToolArchitecture=x64 option (required for 32bit TeamCity builds) on 32 bit builds generally - removes a ton of 'unknown option, ignored' spam in the build output