libziparchive: add trivial fuzzer.

Didn't find anything when I ran it, but it did get me to fix the
const/non-const void* in the API.

Test: treehugger
Change-Id: If3849d974965e3e5ffcbdaf5e47921316d717410
diff --git a/Android.bp b/Android.bp
index 0253f2f..2251479 100644
--- a/Android.bp
+++ b/Android.bp
@@ -184,3 +184,10 @@
     ],
     recovery_available: true,
 }
+
+cc_fuzz {
+    name: "libziparchive_fuzzer",
+    srcs: ["libziparchive_fuzzer.cpp"],
+    static_libs: ["libziparchive", "libbase", "libz", "liblog"],
+    host_supported: true,
+}