There were two distinct LLMemory methods getCurrentRSS() and
getWorkingSetSize(). It was pointless to have both: on Windows they were
completely redundant; on other platforms getWorkingSetSize() always returned
0. (Amusingly, though the Windows implementations both made exactly the same
GetProcessMemoryInfo() call and used exactly the same logic, the code was
different in the two -- as though the second was implemented without awareness
of the first, even though they were adjacent in the source file.)

One of the actual MAINT-6996 problems was due to the fact that
getWorkingSetSize() returned U32, where getCurrentRSS() returns U64. In other
words, getWorkingSetSize() was both useless *and* wrong. Remove it, and change
its one call to getCurrentRSS() instead.

The other culprit was that in several places, the 64-bit WorkingSetSize
returned by the Windows GetProcessMemoryInfo() call (and by getCurrentRSS())
was explicitly cast to a 32-bit data type. That works only when explicitly or
implicitly (using LLUnits type conversion) scaling the value to kilobytes or
megabytes. When the size in bytes is desired, use 64-bit types instead.

In addition to the symptoms, LLMemory was overdue for a bit of cleanup.

There was a 16K block of memory called reserveMem, the comment on which read:
"reserve 16K for out of memory error handling." Yet *nothing* was ever done
with that block! If it were going to be useful, one would think someone would
at some point explicitly free the block. In fact there was a method
freeReserve(), apparently for just that purpose -- which was never called. As
things stood, reserveMem served only to *prevent* the viewer from ever using
that chunk of memory. Remove reserveMem and the unused freeReserve().

The only function of initClass() and cleanupClass() was to allocate and free
reserveMem. Remove initClass(), cleanupClass() and the LLCommon calls to them.

In a similar vein, there was an LLMemoryInfo::getPhysicalMemoryClamped()
method that returned U32Bytes. Its job was simply to return a size in bytes
that could fit into a U32 data type, returning U32_MAX if the 64-bit value
exceeded 4GB. Eliminate that; change all its calls to getPhysicalMemoryKB()
(which getPhysicalMemoryClamped() used internally anyway). We no longer care
about any platform that cannot handle 64-bit data types.

LLPrivateMemoryPool and LLPrivateMemoryPoolManager have assumed that it's
always valid to cast a pointer to U32. With 64-bit pointers, no longer true.

- fix for review
- fix in buffer overrun detector

less than allowed. Changes in all other files relate auxiliary methods for
catching similar bugs in future.

also, fixed alignment of tick labels on stat bars

removed complicated and unnecessary fast timer gapless handoff logic (it should be gapless anyway)
improved MemTrackable API, better separation of shadow and footprint
added memory usage stats to floater_stats.xml

changed unit declarations macros to make a lot more sense

continued conversion to units system
made units perform type promotion correctly and preserve type in arithmetic
e.g. can now do LLVector3 in units
added typedefs for remaining common unit types, including implicits

converted many values over to units system in effort to track down
source of 0 ping

added percentage/ratio units
added auto-range and auto tick calculation to stat bar to automate display stats

Move fast memcpy to llcommon and use it in llalignedarray pushback on all platforms. Code Review: DaveP

Reviewed by Graham

made LLTrace::MemTrackable support custom alignment
LLDrawable now uses MemTrackable new and delete operators

fix for compile error on windows
ignore stdint.h even though VS2010 provides it

fixes to merge

MAINT-1753: Correcting behavior of ll_aligned_realloc_16() on Linux to avoid memory corruption in the case that the new memory size requested is smaller than the old memory size.  Also, adding check to ensure that the aligned malloc returns a non-null value before memcopying.

added LLThreadLocalPtr
broke llmutex out into llmutex.h
got primary sampling buffer under thread local storage