If HTTP charset header is empty, do not append content encoding to Content-Type header
Add unit test for Content-Type header with and without charset set
xbuild: include a Microsoft.Portable.Common.targets file (for F#)

F# PCL projects expect this file to exist in:
$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.Common.targets

So in order to avoid pristine F# PCL projects (created from VS) fail
the build that file has to exist, and import the Core targets like
its CSharp counterpart (Microsoft.Portable.CSharp.targets) does.

Fixes https://bugzilla.xamarin.com/show_bug.cgi?id=17906
[Fix] Bugzilla #17897 - MemoryCacheEntryPriorityQueue throws out of bounds after shrink
- when MemoryCacheEntryPriorityQueue grows the timed items after a shrink
  the value of the member variable heapSize is wrong allowing an out-of-
  bounds exception which would normally be prevented by bounds tests
- A test case was added for the out-of-bounds exception
Merge pull request #934 from exony-craigminihan/bugzilla#17897-B

[Fix] Bugzilla #17897 - MemoryCacheEntryPriorityQueue throws out of boun...
[runtime] Fixed flags for VirtualAlloc in mono_valloc (Windows)
Merge pull request #866 from linquize/content-type-encoding

(master) If HTTP charset header is empty, do not append content encoding to Content-Type header
Merge pull request #936 from adahn/master

[runtime] Fixed flags for VirtualAlloc in mono_valloc (Windows)
[corlib] Improve flow of ExecutionContext (few tests taken from https://github.com/mono/mono/pull/864). Fixes #18121 and similar.
[system.net.htt[] Pass CancellationToken in GetAsync. Fixes #13281
Merge pull request #915 from knocte/master

xbuild: include a Microsoft.Portable.Common.targets file (for F#)
[Fix] Bugzilla #18245 - System.Runtime.MemoryCache.GetValues() throws LockRecursionException with expired items
- GetValues() calls MemoryCacheContainer.GetEntry() which now gets an EnterUpgradeableReadLock needed by ExpireIfNeeded()
- Added a test case
[sgen] Change the bridge interface to include richer type information on classes.

There is an additional axis to bridge processing than just if a type is a bridge or not.
It can be processing transparent or opaque.

We didn't make this distinction before and treated all types as transparent.

Opaque types means that bridge processing should stop at them. An opaque bridge, in
addition to that, means it should be reported in.

This change paves the way for bridge graph pruning.
[corlib] Fix culture name constants in CreateSpecificCultureFromNeutral to be all lower case
Update CLDR to version 2.4. Fixes #17615
[runtime] Make different kinds of delegate invokes use a different name.
[io-layer] Bionic doesn't have clock_nanosleep.
[corlib] Fix the mobile profile.
When a read only property and the type is an interface we can't serialize the type.

This change is released under the MIT license.
Add test to ensure using concrete List as readonly property still serializes

This change is released under the MIT license.