[Sys.Data] Add unit tests for Novell bug #519648

These unit tests demonstrate the difference to .NET
(https://bugzilla.novell.com/show_bug.cgi?id=519648).
[Sys.Data] Fix Novell Bug #519648

Don't throw an exception when passing "new object[] {null}" to
DataRowCollection.Find. This makes the behaviour more compatible
with .NET. This fixes bug #519648
(https://bugzilla.novell.com/show_bug.cgi?id=519648).
[System.XML] Add unit test for #18118
[System.XML] Fix handling of global variables in XSLs (#18118)
[System.XML] Add unit test for XSL note-set bug (#18114)
[System.XML] Fix XSL node-set bug (#18114)

XSL node-set function now behaves more like MS version.
[System.XML] Add unit test for XSL value-of bug (#18113)
[System.XML] Fix handling of space in XSL value-of elements (#18113)
[mcs] Adding unit test for #18511
[mcs] Fix recursive resolving of crefs (#18511)
[Fix] Bugzilla #18213 - System.Runtime.Caching.MemoryCache doesn't honor SlidingExpiration
[xbuild] Add GetAssemblyIdentity task to Microsoft.Common.tasks
Emit profiler enter/leave instrumentation calls as icalls.

This is more portable than using the mono_arch_instrument_* functions and
thus isn't prone to nasty arch-specific bugs. In particular, the old way
of instrumenting function prologues/epilogues resulted in a somewhat elusive
stack corruption bug on Android (ARM). Eventually, we should get rid of these
functions entirely and only use icalls, with JIT opcodes for special cases
(such as saving arguments for --trace).

This new way of doing things also makes profiler instrumentation AOT-safe,
since we're now going through the proper channels to emit references to the
runtime functions (mono_profiler_method_enter/leave) and to embed MonoMethod
pointers.

Since we're using icalls without wrappers to do this, there should be no
visible performance impact from this commit.
Merge pull request #961 from ermshiperete/bug-xamarin-18118

[System.XML] XSL bugfixes for #18118 #18114 #18113
[genproj] For Path.GetFullPath to work, we must use convert Windows paths to Unix paths
genproj: add support for Alias in project references
Revert "[counters] Simplify things a bit by removing unsigned counter types."

This reverts commit 2fa83d9a8cef9d5a5c050e40bc2f757dba445997.
[mono-counters] Bring MONO_COUNTER_TIME_INTERVAL back.
[counters] Install mono-counters.h since it's part of the public API.
[counters] Document mono_counters_foreach.