Fix implicit fallthrough warnings treated as errors

Ideally we'd use the [[fallthrough]] attribute to silence this, but that
isn't supported until C++17 and we're sticking with C++11 for now.

Bug b/120382288

Change-Id: I98f28e42505ed496b0b35c29a7dc03fca18cf4ff
Reviewed-on: https://swiftshader-review.googlesource.com/c/23128
Reviewed-by: Greg Hartman <ghartman@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/third_party/llvm-subzero/Android.bp b/third_party/llvm-subzero/Android.bp
index 854fa8d..72c9b32 100644
--- a/third_party/llvm-subzero/Android.bp
+++ b/third_party/llvm-subzero/Android.bp
@@ -28,6 +28,7 @@
         "-D__STDC_CONSTANT_MACROS",
         "-D__STDC_FORMAT_MACROS",
         "-DLOG_TAG=\"libsubzero\"",
+        "-Wno-implicit-fallthrough",
         "-Wno-unused-parameter",
     ],