gn2bp: ignore -Wmacro-redefined

Test: //net:net
Change-Id: Ic252a5657457d92f87018028eef61f735f7b50c8
diff --git a/tools/gn2bp/gen_android_bp b/tools/gn2bp/gen_android_bp
index 1e56d32..c14858b 100755
--- a/tools/gn2bp/gen_android_bp
+++ b/tools/gn2bp/gen_android_bp
@@ -1149,6 +1149,7 @@
   defaults.cflags = [
       '-Wno-error=return-type',
       '-Wno-non-virtual-dtor',
+      '-Wno-macro-redefined',
       '-Wno-missing-field-initializers',
       '-Wno-sign-compare',
       '-Wno-sign-promo',