Fixed NullReferenceExcepton in Socket.Connect for non-IP endpoints

Socket.Connect(EndPoint) throws a NullReferenceException when connecting to non-IP (eg Unix) endpoints in Dgram mode.
Added fix for Bug 20869
[system.data] BUGFIX: fixes issue with expression columns and IsNull:
 - bugzilla.xamarin.com issue 20925
 - if an expression column was added ayer there were rows, and then IsNull is called, the result is incorrect (it will always be true)
[mcs tests] class/Microsoft.JScript does not exist anymore
[system.data] Appended the fix to correct the whitespace Expression and argument checking
 - Whitespace Espressions:
 -- if a column expression is a pure whitespace, use an empty string instead
 -- if a column expression is surrounded by whitespace, preserve whitespace
 -- if a column expression is null/empty, use an empty string
 - Get a row's column value:
 -- make sure we throw exceptions if the column we are looking at is null
 -- make sure we throw exceptions if we can't find the column with the provided name
[mcs] Use same rules in dynamic context as in normal instance member hidding.
[mcs] Emit partial type parameters attributes too
[amd64] Fix the popping of LMF frames during unwinding. Fixes #20616.
[jit] Move the 'remove any unused lmf' code from mono_arch_find_jit_info () to mini-exceptions.c to reduce code duplication and fix some problems where ctx->sp and lmf->sp was used to determine whenever the LMF was below the end of the stack instead of new_ctx->sp and lmf.
Merge pull request #1133 from kitsilanosoftware/mcs-tests-no-jscript

[mcs tests] class/Microsoft.JScript does not exist anymore
[mcs] Not applicable GetEnumerator candidates were not rejected early enough
[System.Web] Tests: Fix deadlock when ThreadAbortException is thrown

This reverts commit ed11296c511d670391374fbb68e2988a9c1e8789.

When a ThreadAbortException is thrown during request processing in AsyncRun () the _done.Set () call is not executed.
This then results in a deadlock because _done.WaitOne () doesn't get signaled and waits forever.
One solution would be enclosing the _done.Set () in a finally clause, but even then we'd need to relaunch the AsyncRun () loop to be in a usable state.

A simpler solution is to revert the commit that introduced the AsyncRun () in the first place, as it doesn't seem necessary now (the tests pass just fine without it).

The test that was disabled in 429cdf17cf3a4887d9882380beebbf0d119e65ab is reenabled too, as it wasn't the culprit of the problem.
Merge pull request #1138 from akoeplinger/fix-webtest-deadlocks

[System.Web] Tests: Fix deadlock when ThreadAbortException is thrown
[amd64] Remove the callee saved registers from MonoLMF, save/restore them normally using the normal register save/restore code.
Emit correct memory barriers in the JIT intrinsic for Interlocked.Read ().
Add /reflection-load-dir to mono/tests/.gitignore.
[dist] Do not include .git link files in dist tarball

Recent versions of Git co-host submodule GIT_DIRs in <root-project>/.git/
by default, and write their relative path into <subproject>/.git,
which is a regular file:

    $ ls -l external/cecil/.git
    -rw-r--r-- 1 foo  bar  42 Jun 16 12:50 external/cecil/.git
    $ cat external/cecil/.git
    gitdir: ../../.git/modules/external/cecil

Relax the expression in Makefile.am to also delete these (broken)
"symlinks" when preparing a distribution tarball.
Merge pull request #1140 from kitsilanosoftware/no-gitlink-in-dist

[dist] Do not include .git link files in dist tarball
Allocate the finalizable object in finalizer-exception.cs in another thread to make it less likely that it is retained. Fixes finalizer-exception.exe on 64 bit osx+llvm.
[mcs] Re-add obsolete reporting for enumerators removed in 6643bc119cbe1e94b5634e6452dd6eb40c7681c7