Pad the page containing ARM code in the JIT code cache to work around a CPU bug.

Bug: 2501147

Verified with seeing the following line in the log. The 4096 number confirms
that the ARM handler code is using a full page.

D/dalvikvm(  369): 21 compilations using 4096 + 1288 bytes

Change-Id: I89e1473ce9a4353f58f740e1c86d358d3fec33b2