Merge pull request dotnet/coreclr#6521 from adityamandaleeka/remove_internal_free

Remove CorUnix::InternalFree from PAL

Commit migrated from https://github.com/dotnet/coreclr/commit/b49116c0f940760c49b2af9b7593e38a11921694

diff --cc src/coreclr/src/pal/src/debug/debug.cpp
Simple merge

diff --cc src/coreclr/src/pal/src/exception/machexception.cpp
Simple merge

diff --cc src/coreclr/src/pal/src/thread/thread.cpp
Simple merge