[Wconversion] Suppress warnings

Bug: 58162
Change-Id: Ib2e8ad1d1649c7328e6b2e5902a0f76465057179
diff --git a/BUILD.gn b/BUILD.gn
index ef82879..fe0d1f1 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -116,6 +116,7 @@
     "-Wno-unused-function",
     "-Wno-unused-value",
     "-Wno-unused-variable",
+    "-Wno-conversion",
   ]
 
   ldflags = [ "-static-libstdc++" ]