[libfuzzer] Add fuzzer for third_party/hunspell with dictionary.

third_party/hunspell/BUILD.gn

Index: third_party/hunspell/BUILD.gn
diff --git a/third_party/hunspell/BUILD.gn b/third_party/hunspell/BUILD.gn
index d086c00d8ba6090de96997df13f326c33e73bdac..4d9fce19a75ce56d6d7368571e4a3362381e4c65 100644
--- a/third_party/hunspell/BUILD.gn
+++ b/third_party/hunspell/BUILD.gn
@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//testing/libfuzzer/fuzzer_test.gni")
+
 config("hunspell_config") {
   defines = [
     "HUNSPELL_STATIC",
@@ -109,3 +111,16 @@ source_set("hunspell") {
     ]
   }
 }
+
+fuzzer_test("hunspell_fuzzer") {
+  sources = [
+    "fuzz/hunspell_fuzzer.cc",
+    "fuzz/hunspell_fuzzer_dictionary.h",
+  ]
+  deps = [
+    ":hunspell",
+  ]
+
+  # This is a dictionary for the fuzzer, not a spellcheck dictionary.
+  dict = "fuzz/hunspell.dict"
+}