Remove unreferenced win_dbghelp.

This appears to be obsolete; it didn't show up anywhere in our code
or build files.

Change-Id: I15ad44c4a76f64da401d2c3c57f43e00e353354e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/596217
Reviewed-by: Ben Wagner <bungeman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
2 files changed