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

# Conflicts:
#	indra/newview/llmachineid.cpp

A shocking number of LLSingleton subclasses had public constructors -- and in
several instances, were being explicitly instantiated independently of the
LLSingleton machinery. This breaks the new LLSingleton dependency-tracking
machinery. It seems only fair that if you say you want an LLSingleton, there
should only be ONE INSTANCE!

Introduce LLSINGLETON() and LLSINGLETON_EMPTY_CTOR() macros. These handle the
friend class LLSingleton<whatevah>;
and explicitly declare a private nullary constructor.

To try to enforce the LLSINGLETON() convention, introduce a new pure virtual
LLSingleton method you_must_use_LLSINGLETON_macro() which is, as you might
suspect, defined by the macro. If you declare an LLSingleton subclass without
using LLSINGLETON() or LLSINGLETON_EMPTY_CTOR() in the class body, you can't
instantiate the subclass for lack of a you_must_use_LLSINGLETON_macro()
implementation -- which will hopefully remind the coder.

Trawl through ALL LLSingleton subclass definitions, sprinkling in
LLSINGLETON() or LLSINGLETON_EMPTY_CTOR() as appropriate. Remove all explicit
constructor declarations, public or private, along with relevant 'friend class
LLSingleton<myself>' declarations. Where destructors are declared, move them
into private section as well. Where the constructor was inline but nontrivial,
move out of class body.

Fix several LLSingleton abuses revealed by making ctors/dtors private:

LLGlobalEconomy was both an LLSingleton and the base class for
LLRegionEconomy, a non-LLSingleton. (Therefore every LLRegionEconomy instance
contained another instance of the LLGlobalEconomy "singleton.") Extract
LLBaseEconomy; LLGlobalEconomy is now a trivial subclass of that.
LLRegionEconomy, as you might suspect, now derives from LLBaseEconomy.

LLToolGrab, an LLSingleton, was also explicitly instantiated by
LLToolCompGun's constructor. Extract LLToolGrabBase, explicitly instantiated,
with trivial subclass LLToolGrab, the LLSingleton instance.

(WARNING: LLToolGrabBase methods have an unnerving tendency to go after
LLToolGrab::getInstance(). I DO NOT KNOW what should be the relationship
between the instance in LLToolCompGun and the LLToolGrab singleton instance.)

LLGridManager declared a variant constructor accepting (const std::string&),
with the comment:
// initialize with an explicity grid file for testing.
As there is no evidence of this being called from anywhere, delete it.

LLChicletBar's constructor accepted an optional (const LLSD&). As the LLSD
parameter wasn't used, and as there is no evidence of it being passed from
anywhere, delete the parameter.

LLViewerWindow::shutdownViews() was checking LLNavigationBar::
instanceExists(), then deleting its getInstance() pointer -- leaving a
dangling LLSingleton instance pointer, a land mine if any subsequent code
should attempt to reference it. Use deleteSingleton() instead.

~LLAppViewer() was calling LLViewerEventRecorder::instance() and then
explicitly calling ~LLViewerEventRecorder() on that instance -- leaving the
LLSingleton instance pointer pointing to an allocated-but-destroyed instance.
Use deleteSingleton() instead.

This fixes fatal warnings.

MAINT-6403: in the case of a version mismatch between the viewer's local accounting and the AIS reported. Override with the AIS version. simplify the appearance update code to account for new versioning. Fix spelling of descendant

MAINT-6305: Serialize the AIS calls by reducing the queue size to 1, move the bake request out of the AIS queue.

Added exponential timeout to retry, protect against attempting to downgrade the COF version in the bake request.

MAINT-5693: Some bake requests were getting lost. If a bake request is made while another one is outstanding rather than launch the new one, set a flag and remake the request with new data.

MAINT-5693: Consolidated the avatar appearance request into a coroutine.  If the request fails because of a stale COF, then rerequest with the corrected one.

Changed language, appearance, and maturity to conform to use the adapter rather than the SDHandler

MAINT-5082 WIP, MAINT-5083 WIP - consolidate COF link creation calls during mass add of wearables/objects

Adding llagentlanguage to new LLCore::Http code moved some of llappearancemgr handling into llAgent.

Prep for some slight cleanup of the code.
Add AP_AVATAR Policy

SL-103 WIP - viewer enforces wearable limits based on total articles of clothing rather than per-type limit. Limit is artificially low for testing, will bump before release.

MAINT-4653, DRTVWR-397 WIP - more code for tracking attachment operations, smarter handling of multiple requests.

SH-4422 WIP - avoid redundant calls to updateAppearanceFromCOF() if rezzing an attachment that's already linked in COF

SH-4455 WIP - restrict use of LLWearableHoldingPattern metrics. When changing wearables, bail out if current wearables already match those requested.

SH-4226 WIP - try to be smarter about when to send appearance update requests, removed many redundant calls