Port Ordinal Ignore Case Optimization changes

[tarekgh]

This is porting the changes from the PR #40910.

[ghost]

Tagging subscribers to this area: @tarekgh, @safern, @krwq
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[tarekgh]

#37919
#26054
#40942

[tarekgh]

@safern @GrabYourPitchforks this is straight porting the changes you have approved to RC1 branch.

CC @danmosemsft @ericstj @Anipik

[danmoseley]

Port approved

[GrabYourPitchforks]

Thanks Tarek! 😸

[tarekgh]

The failure in the CI is tracked by the issue #39009

https://helix.dot.net/api/2019-06-17/jobs/61043e95-3b03-4c8c-bf90-1b1b5cf6fb28/workitems/System.DirectoryServices.Protocols.Tests/console%20

ushd .
/home/helixbot/work/A434096D/p/dotnet exec --runtimeconfig System.DirectoryServices.Protocols.Tests.runtimeconfig.json --depsfile System.DirectoryServices.Protocols.Tests.deps.json xunit.console.dll System.DirectoryServices.Protocols.Tests.dll -xml testResults.xml -nologo -nocolor -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing 
popd
===========================================================================================================
~/work/A434096D/w/A872094B/e ~/work/A434096D/w/A872094B/e
  Discovering: System.DirectoryServices.Protocols.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.DirectoryServices.Protocols.Tests (found 343 of 369 test cases)
  Starting:    System.DirectoryServices.Protocols.Tests (parallel test collections = on, max threads = 2)
dotnet: ../nptl/pthread_mutex_lock.c:79: __pthread_mutex_lock: Assertion `mutex->__data.__owner == 0' failed.
./RunTests.sh: line 161: 95592 Aborted                 "$RUNTIME_PATH/dotnet" exec --runtimeconfig System.DirectoryServices.Protocols.Tests.runtimeconfig.json --depsfile System.DirectoryServices.Protocols.Tests.deps.json xunit.console.dll System.DirectoryServices.Protocols.Tests.dll -xml testResults.xml -nologo -nocolor -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing $RSP_FILE
~/work/A434096D/w/A872094B/e
----- end Tue Aug 18 17:35:36 UTC 2020 ----- exit code 134 ----------------------------------------------------------
exit code 134 means SIGABRT Abort. Managed or native assert, or runtime check such as heap corruption, caused call to abort(). Core dumped.