[Wconversion] Suppress warnings

Bug: 56258
Bug: 58162
Change-Id: I7edcf00edd9b999161182b7d93d4ce792fff1352
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/sbase/+/426034
Reviewed-by: Shai Barack <shayba@google.com>
Reviewed-by: Petr Hosek <phosek@google.com>
diff --git a/libutf/BUILD.gn b/libutf/BUILD.gn
index b134c5f..f8894fa 100644
--- a/libutf/BUILD.gn
+++ b/libutf/BUILD.gn
@@ -25,4 +25,7 @@
     "utf.c",
     "utftorunestr.c",
   ]
+
+  # Suppress warnings in upstream code that are triggered by Fuchsia compilation flags.
+  cflags = [ "-Wno-conversion" ]
 }
diff --git a/libutil/BUILD.gn b/libutil/BUILD.gn
index 2cbda26..11c5eab 100644
--- a/libutil/BUILD.gn
+++ b/libutil/BUILD.gn
@@ -3,9 +3,11 @@
 # found in the LICENSE file.
 
 config("libutil_config") {
+  # Suppress warnings in upstream code that are triggered by Fuchsia compilation flags.
   cflags = [
     "-Wno-sign-compare",
     "-Wno-constant-conversion",
+    "-Wno-conversion",
   ]
 }