Remove -D_FILE_OFFSET_BITS=64 on host builds

This prevents us from using glibc's <fts.h> because of
https://sourceware.org/bugzilla/show_bug.cgi?id=11460,
and we now only support 64-bit hosts.

Bug: 139544611
Test: Treehugger
Change-Id: Iaacc9ea17473201bf3d701e82081264921062d5e
diff --git a/base/Android.bp b/base/Android.bp
index 357ce01..f5000c1 100644
--- a/base/Android.bp
+++ b/base/Android.bp
@@ -20,8 +20,14 @@
         "-Wall",
         "-Werror",
         "-Wextra",
-        "-D_FILE_OFFSET_BITS=64",
     ],
+    target: {
+        android: {
+            cflags: [
+                "-D_FILE_OFFSET_BITS=64",
+            ],
+        },
+    },
 }
 
 cc_library_headers {