libbinder: disable implicit unique_fd get

Considered dangerous, since we will be using more unique_fd here soon.

Bug: N/A
Test: build
Change-Id: I35dcbb889527cdbfd16e7feb9c2611fe3cb11f68
diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index e0d5378..45e9775 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -146,6 +146,7 @@
         "-Wextra",
         "-Werror",
         "-Wzero-as-null-pointer-constant",
+        "-DANDROID_BASE_UNIQUE_FD_DISABLE_IMPLICIT_CONVERSION",
     ],
     product_variables: {
         binder32bit: {