[GWP-ASan] Allow libc header access from GWP-ASan.

GWP-ASan is part of libc, and the tests (in future) will have to access
the internal headers of libc (particularly, the frame pointer unwinder).

Allow GWP-ASan to have access to the header package.

Bug: 152414185
Test: N/A
Change-Id: I09f771a667be867ec0acc90ddd6b52a432098c57
diff --git a/libc/Android.bp b/libc/Android.bp
index 4d35592..8e0e0a9 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1747,6 +1747,7 @@
         "//art:__subpackages__",
         "//bionic:__subpackages__",
         "//frameworks:__subpackages__",
+        "//external/gwp_asan:__subpackages__",
         "//external/perfetto:__subpackages__",
         "//external/scudo:__subpackages__",
         "//system/core/debuggerd:__subpackages__",