Disable -Wno-single-bit-bitfield-constant-conversion locally

...so it can be enabled globally.

Bug: 243965903
Test: presubmit
Change-Id: I795a1a9e9066e9034c3612efad9d1435acd91e91
diff --git a/Android.bp b/Android.bp
index 6d59c06..fd36b23 100644
--- a/Android.bp
+++ b/Android.bp
@@ -77,6 +77,7 @@
         "-Wno-null-pointer-arithmetic",
         "-Wno-register",
         "-Wno-shift-count-overflow",
+        "-Wno-single-bit-bitfield-constant-conversion",
         "-Wno-sign-compare",
         "-Wno-strict-prototypes",
         "-Wno-tautological-compare",