gn2bp: Add flag to fix zlib for compiling on clang

Test: m cronet_aml_third_party_zlib_zlib
Change-Id: I40de0f9b48dd6341753e2013ce75ce02be058479
diff --git a/tools/gn2bp/gen_android_bp b/tools/gn2bp/gen_android_bp
index 0ca97c6..47232a1 100755
--- a/tools/gn2bp/gen_android_bp
+++ b/tools/gn2bp/gen_android_bp
@@ -1239,6 +1239,7 @@
       '-Wno-sign-compare',
       '-Wno-sign-promo',
       '-Wno-unused-parameter',
+      '-Wno-deprecated-non-prototype', # needed for zlib
       '-fvisibility=hidden',
       '-O2',
   ]