[Fuchsia] Set perfetto_unittests for CFv1

Needed to support test filter file.

Change-Id: I37d449728fcada5ffe371baf964b9d7db1bf4d5e
diff --git a/BUILD.gn b/BUILD.gn
index 2e07e14..dc716f8 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -77,6 +77,9 @@
 if (enable_perfetto_unittests) {
   import("gn/perfetto_unittests.gni")
   test("perfetto_unittests") {
+    if (is_fuchsia) {
+      use_cfv2 = false
+    }
     deps = perfetto_unittests_targets
   }
   all_targets += [ ":perfetto_unittests" ]