Use -Werror in external/bzip2

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I0a2edf629260d179476903548c1a1c4a6a4df594
diff --git a/Android.bp b/Android.bp
index 897dc77..c9c0e13 100644
--- a/Android.bp
+++ b/Android.bp
@@ -25,6 +25,7 @@
     cflags: [
         "-O3",
         "-DUSE_MMAP",
+        "-Werror",
         "-Wno-unused-parameter",
     ],
     export_include_dirs: ["."],
@@ -49,6 +50,7 @@
     static_libs: ["libbz"],
     stl: "none",
     cflags: [
+        "-Werror",
         "-Wno-unused-parameter",
     ],
     symlinks: [