Compile with -D_FILE_OFFSET_BITS to support 32-bit userspace

This is to support when partition sizes are greater than 2GB (2^31)
on 32-bit userspace.

Bug: 300178204
Test: OTA on device with 32-bit userspace + product partition > 2GB
Ignore-AOSP-First: Cherrypick from AOSP
Change-Id: I7074682352d8388ed410c684cb7cb0fa346ba24c
Signed-off-by: Akilesh Kailash <akailash@google.com>

fs_mgr/libsnapshot/snapuserd/Android.bp

@@ -96,6 +96,10 @@ cc_defaults {
         "user-space-merge/snapuserd_server.cpp",
     ],
 
+    cflags: [
+        "-D_FILE_OFFSET_BITS=64",
+    ],
+
     static_libs: [
         "libbase",
         "libbrotli",