[Wconversion] Suppress warnings

Bug: 58162
Change-Id: I6af62c9fde1d201561fd78e6bff62b84271f68eb
diff --git a/BUILD.gn b/BUILD.gn
index bc6b7fa..75cb50a 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -4,6 +4,7 @@
 
 config("farmhash_config") {
   defines = [ "NAMESPACE_FOR_HASH_FUNCTIONS=farmhash" ]
+  cflags = [ "-Wno-conversion" ]
 }
 
 source_set("farmhash") {
@@ -11,6 +12,5 @@
     "src/farmhash.cc",
     "src/farmhash.h",
   ]
-  cflags = [ "-Wno-conversion" ]
   public_configs = [ ":farmhash_config" ]
 }