pw_fuzzer: Fix adding the fuzzer dep

The pw_fuzzer dependency was only added to pw_fuzzer targets if the
targets didn't specify any deps.

Change-Id: I7030c6d869c8960da9de892a4746421bfdd0eb6f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/44801
Pigweed-Auto-Submit: Wyatt Hepler <hepler@google.com>
Reviewed-by: Rob Mohr <mohrr@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>

pw_fuzzer/fuzzer.gni

diff --git a/pw_fuzzer/fuzzer.gni b/pw_fuzzer/fuzzer.gni
index de7d6c6..fcd15e4 100644
--- a/pw_fuzzer/fuzzer.gni
+++ b/pw_fuzzer/fuzzer.gni
@@ -48,8 +48,9 @@
       forward_variables_from(invoker, [ "visibility" ])
 
       if (!defined(deps)) {
-        deps += [ dir_pw_fuzzer ]
+        deps = []
       }
+      deps += [ dir_pw_fuzzer ]
 
       if (!defined(configs)) {
         configs = []