win: Fix -Wmicrosoft-cast warning
win: Fix -Wmicrosoft-cast warning

Standard C++ doesn't allow implicit conversion between function
pointers and void*. MSVC does allow that, so clang-cl also allows it
but emits a -Wmicrosoft-cast warning. We want to enable this warning to
make the compiler behave more similar on different platforms, so add an
explicit cast to void*. (GetProcAddress() returns FARPROC, a function
pointer type.)

Upstreamed from:
https://chromium-review.googlesource.com/c/chromium/src/+/953743

Change-Id: I3ed4e23395e1e01b31b7cf945ddb6f93e4e69d45
Reviewed-on: https://chromium-review.googlesource.com/959545
Commit-Queue: Joshua Peraza <f5809a5e35ec7e1bd0e25cb0a0b68bb433cf6f17@chromium.org>
Reviewed-by: Mark Mentovai <f1b5a91d4d6ad523f2610114591c007e75d15084@chromium.org>

chromium/crashpad,chromium/crashpad,chromium/crashpad