Fixed issue #3987 "Debugger fails to stop on entry due to stack walk failure"

[mikem8361]

By initializing m_rgHijackFunction to NULL.

[mikem8361]

@noahfalk, @jkotas and @sergiy-k code review?

@gregg-miskelly can you verify this fixes the problem?

[gregg-miskelly]

Linux is verified. I am working on verifying OSX.

[mikem8361]

Thanks.

[gregg-miskelly]

OSX works as well. Woohoo!

[mellinoe]

OSX CI failed. Is that expected?

[mikem8361]

The OSX test failure was a paltest:
foo 0000bfoo bfoo b.foo 42foo 65535foo -1foo 42foo 42foo 42foo 42 foo 42foo 042foo 042foo 42foo +42foo 42foo -42foo -42.foo 42foo 65535foo -1foo 42foo 42foo 42foo 42 foo 42foo 042foo 042foo 42foo +42foo 42foo -42foo -42..............Testing for 64 Bit Platforms
17:42:51 ..................Testing for 64 Bit Platforms
17:42:51 ...............................hello world..................................Testing for 64 Bit Platforms
17:42:53 ..................Testing for 64 Bit Platforms
17:42:53 .......................Testing for 64 Bit Platforms
17:42:54 ..................Testing for 64 Bit Platforms
17:42:54 ..........................................................................................................DeleteFileA: ERROR: Couldn't delete DeleteFileA's "testFile01.txt"
17:42:57
17:42:57
17:42:57 FAILED: file_io/DeleteFileA/test1/paltest_deletefilea_test1. Exit code: 1
17:42:57

This has nothing to do with my change and it passed locally. Rerunning the OSX leg.

[mikem8361]

@dotnet-bot test OSX x64 Checked Build and Test

[noahfalk]

lgtm