More Mac build fixes.

The libziparchive public headers that refer to `off64_t` also need the
Mac workaround.

In fastboot, there's a stray `lseek64` but since it's only for offset 0,
any kind of seek is fine.

Bug: N/A
Test: builds
Change-Id: I68b4f95202623ebf07ffe6c3e0e21437e7922c5b
diff --git a/libziparchive/Android.bp b/libziparchive/Android.bp
index 608afb7..2095189 100644
--- a/libziparchive/Android.bp
+++ b/libziparchive/Android.bp
@@ -73,6 +73,7 @@
         enabled: true,
     },
     double_loadable: true,
+    export_shared_lib_headers: ["libbase"],
 
     defaults: [
         "libziparchive_defaults",