Changes needed to run on OSS-Fuzz.

Bump libunwindstack to build with system libc++.

Bug: 69150303
Change-Id: I6a4fae6bb201f0e2164a6d04ad116f1b61e3bf0f
diff --git a/gn/standalone/BUILD.gn b/gn/standalone/BUILD.gn
index 863b972..7c1e56d 100644
--- a/gn/standalone/BUILD.gn
+++ b/gn/standalone/BUILD.gn
@@ -191,7 +191,7 @@
   ]
   if (is_android) {
     cflags += [ "-Oz" ]
-  } else if (use_libfuzzer) {
+  } else if (is_fuzzer) {
     cflags += [ "-O1" ]
   } else {
     cflags += [ "-O3" ]