[fuchsia] Suppress conversion errors

Change-Id: Ifb512fabaaecc3d38554a12b205fd162d84c63bb
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/benchmark/+/446996
Reviewed-by: Tamir Duberstein <tamird@google.com>

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
index c5aa2df..4cb9f78 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -29,4 +29,5 @@
     "HAVE_POSIX_REGEX",
     "HAVE_THREAD_SAFETY_ATTRIBUTES",
   ]
+  configs += [ "//build/config:Wno-conversion" ]
 }