* Security fix for ASP.NET (XSP / mod_mono) source code disclosure
(CVE-2010-4225)
* Backport ParallelFx improvements from master (jlaval)
* Fix state check for short-circuiting with SupportRecursion in
ReaderWriterLockSlim #655361 (jlaval)
* Increment Count even on single-processor in SpinWait.
Fix#624849. (jlaval)
* Update ThreadLocal to use default(T) for initialization with
parameterless ctor. Fix#658689. (jlaval)
This changes the buildlink3.mk files to use an include guard for the
recursive include. The use of BUILDLINK_DEPTH, BUILDLINK_DEPENDS,
BUILDLINK_PACKAGES and BUILDLINK_ORDER is handled by a single new
variable BUILDLINK_TREE. Each buildlink3.mk file adds a pair of
enter/exit marker, which can be used to reconstruct the tree and
to determine first level includes. Avoiding := for large variables
(BUILDLINK_ORDER) speeds up parse time as += has linear complexity.
The include guard reduces system time by avoiding reading files over and
over again. For complex packages this reduces both %user and %sys time to
half of the former time.