gn2bp: Add an helper to drop unneeded third_party dependencies

Use a more expressive always_disable function to disable unneeded
third_party dependencies.

Test: Android.bp.swp output is equivalent
Change-Id: Ib21646dfa076fc6f745b7871851744d6ed18eaf3
diff --git a/tools/gn2bp/gen_android_bp b/tools/gn2bp/gen_android_bp
index d8e12de..b48a05b 100755
--- a/tools/gn2bp/gen_android_bp
+++ b/tools/gn2bp/gen_android_bp
@@ -190,6 +190,9 @@
     ],
 }
 
+def always_disable(module, arch):
+  return None
+
 def enable_brotli(module, arch):
   # Requires crrev/c/4111690
   if arch is None:
@@ -227,17 +230,17 @@
 # depends on.
 builtin_deps = {
     '//buildtools/third_party/libunwind:libunwind':
-        lambda m, a: None, # disable libunwind
+        always_disable,
     '//buildtools/third_party/libunwind:libunwind__testing':
-        lambda m, a: None, # disable libunwind
+        always_disable,
     '//net/data/ssl/chrome_root_store:gen_root_store_inc':
-        lambda m, a: None,
+        always_disable,
     '//net/data/ssl/chrome_root_store:gen_root_store_inc__testing':
-        lambda m, a: None,
+        always_disable,
     '//net/tools/root_store_tool:root_store_tool':
-        lambda m, a: None,
+        always_disable,
     '//net/tools/root_store_tool:root_store_tool__testing':
-        lambda m, a: None,
+        always_disable,
     '//third_party/zlib:zlib':
         enable_zlib,
     '//third_party/zlib:zlib__testing':