Use IPPROTO_TCP instead of SOL_TCP for cross-platform compatibility.
Fix race condition in WebConnectionStream

See https://bugzilla.xamarin.com/show_bug.cgi?id=1553
[xbuild] Actually delete common files (CopyLocal) during Clean.

The common files that should be deleted during Clean (see 4c37deb)
weren't actually written to the CleanFile, as they were stored in
FileWrites after it was already used to create CombinedFileWrites.
xbuild: use the AdditionalReferencePath items to locate assemblies

This is a little underdocumented feature of MSBuild. Items with the name
"AdditionalReferencePath" get searched for referenced assemblies. This helps
with some scenarios, e.g. when the assembly has to be references from a central
location.
Eliminate the use of localloc in gsharedvt methods which have no gsharedvt locals.
Add specialized memcpy/bzero methods to String which are called from gsharedvt code.
Handle shifts by multiple of 32 correctly. Fixes #10887.
Optimize generated gsharedvt code: Load information from the gsharedvt_info variable instead of using an rgctx fetch trampoline, use optimized memcpy/bzero methods.
Allow the gsharedvt info/local vars to be register allocated.
[PCL]: System.Windows and System.Xml.Serialization are no Facade Assemblies.
Better handle default value BigInteger. Fixes #11945
Fix delegate combine when left side has already been invoked.
Fix new BigInteger().GetHashCode() to not throw.
Allow Nullable.Box/Unbox to be compiled as gsharedvt methods.
Fix the arm build.
Add System.Net to runtime remapping list.
Bump ikvm to 10b8312c8024111780ee382688cd4c8754b1f1ac.
Add support for nullables to box/unbox in gsharedvt code.
Revert "Add beginnings of a managed IL disassembler which uses Mono.Cecil. Not yet part of the build."

This reverts commit 535e76a05898eb0bb62932f12c145ad02c215f64.

Revert this as we will be using something else.
Reverted whitespace changes