No omit-frame-pointer on Win

Bug: skia:
Change-Id: I0dda67283b32aaf06a34463847e760158bf47392
Reviewed-on: https://skia-review.googlesource.com/102422
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
diff --git a/gn/BUILD.gn b/gn/BUILD.gn
index 0897e23..b255eba 100644
--- a/gn/BUILD.gn
+++ b/gn/BUILD.gn
@@ -245,9 +245,11 @@
     cflags += [
       "-fsanitize=$sanitizers",
       "-fno-sanitize-recover=$sanitizers",
-      "-fno-omit-frame-pointer",
       "-fsanitize-blacklist=" + rebase_path("../tools/xsan.blacklist"),
     ]
+    if (!is_win) {
+      cflags += [ "-fno-omit-frame-pointer" ]
+    }
     ldflags += [ "-fsanitize=$sanitizers" ]
     if (sanitizers == "memory") {
       cflags += [ "-fsanitize-memory-track-origins" ]