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/libziparchive/zip_archive.cc b/libziparchive/zip_archive.cc
index c95b035..3a552d8 100644
--- a/libziparchive/zip_archive.cc
+++ b/libziparchive/zip_archive.cc
@@ -178,7 +178,7 @@
 #endif
 }
 
-ZipArchive::ZipArchive(void* address, size_t length)
+ZipArchive::ZipArchive(const void* address, size_t length)
     : mapped_zip(address, length),
       close_file(false),
       directory_offset(0),
@@ -471,7 +471,7 @@
   return OpenArchiveInternal(archive, fileName);
 }
 
-int32_t OpenArchiveFromMemory(void* address, size_t length, const char* debug_file_name,
+int32_t OpenArchiveFromMemory(const void* address, size_t length, const char* debug_file_name,
                               ZipArchiveHandle* handle) {
   ZipArchive* archive = new ZipArchive(address, length);
   *handle = archive;
@@ -1152,7 +1152,7 @@
   return fd_;
 }
 
-void* MappedZipFile::GetBasePtr() const {
+const void* MappedZipFile::GetBasePtr() const {
   if (has_fd_) {
     ALOGW("Zip: MappedZipFile doesn't have a base pointer.");
     return nullptr;
@@ -1188,13 +1188,14 @@
       ALOGE("Zip: invalid offset: %" PRId64 ", data length: %" PRId64 "\n", off, data_length_);
       return false;
     }
-    memcpy(buf, static_cast<uint8_t*>(base_ptr_) + off, len);
+    memcpy(buf, static_cast<const uint8_t*>(base_ptr_) + off, len);
   }
   return true;
 }
 
-void CentralDirectory::Initialize(void* map_base_ptr, off64_t cd_start_offset, size_t cd_size) {
-  base_ptr_ = static_cast<uint8_t*>(map_base_ptr) + cd_start_offset;
+void CentralDirectory::Initialize(const void* map_base_ptr, off64_t cd_start_offset,
+                                  size_t cd_size) {
+  base_ptr_ = static_cast<const uint8_t*>(map_base_ptr) + cd_start_offset;
   length_ = cd_size;
 }