[master] Update dependencies from dotnet/coreclr (dotnet/corefx#41089)

* Update dependencies from https://github.com/dotnet/coreclr build 20190912.7

- Microsoft.NET.Sdk.IL - 5.0.0-alpha1.19462.7
- Microsoft.NETCore.ILAsm - 5.0.0-alpha1.19462.7
- Microsoft.NETCore.Runtime.CoreCLR - 5.0.0-alpha1.19462.7

* Fix Environment.WorkingSet tests for coreclr update


Commit migrated from dotnet/corefx@a3dbe06

src/libraries/System.Runtime.Extensions/tests/System/EnvironmentTests.cs

@@ -179,19 +179,11 @@ public void Version_Valid()
         }
 
         [Fact]
-        [SkipOnTargetFramework(TargetFrameworkMonikers.Uap)] // Throws InvalidOperationException in Uap as NtQuerySystemInformation Pinvoke is not available
         public void WorkingSet_Valid()
         {
             Assert.True(Environment.WorkingSet > 0, "Expected positive WorkingSet value");
         }
 
-        [Fact]
-        [SkipOnTargetFramework(~TargetFrameworkMonikers.Uap)]
-        public void WorkingSet_Valid_Uap()
-        {
-            Assert.Throws<PlatformNotSupportedException>(() => Environment.WorkingSet);
-        }
-
         [Trait(XunitConstants.Category, XunitConstants.IgnoreForCI)] // fail fast crashes the process
         [OuterLoop]
         [Fact]