Use -Werror in external/Microsoft-GSL am: fd31217fe1
am: 9ee9d331fb

Change-Id: I1b971dfe48068f6425a009ba1c87b688e5f99386
diff --git a/Android.bp b/Android.bp
index a8538b2..2909031 100644
--- a/Android.bp
+++ b/Android.bp
@@ -19,6 +19,7 @@
     name: "libgsl",
     host_supported: true,
     export_include_dirs: ["include"],
+    cflags: ["-Wall", "-Werror"],
 }
 
 // Tests pending approval of external/Microsoft-unittest-cpp: http://b/32512867