[Wconversion] Suppress warnings

Bug: 56258
Bug: 58162
Change-Id: I9a4080818876d2db7a69ae6283e1517550e2f565
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/expat/+/425959
Reviewed-by: Petr Hosek <phosek@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index 81e102e..d192d6c 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -12,9 +12,7 @@
 
 source_set("expat") {
   public_configs = [ ":expat_config" ]
-  public = [
-    "expat/lib/expat.h",
-  ]
+  public = [ "expat/lib/expat.h" ]
   sources = [
     "expat/lib/amigaconfig.h",
     "expat/lib/ascii.h",
@@ -37,4 +35,5 @@
     "expat/lib/xmltok_impl.h",
     "expat/lib/xmltok_ns.c",
   ]
+  cflags = [ "-Wno-conversion" ]
 }