Fixing segfault crash in x86_64 get_size testcase am: 11c0034821 am: 34dab56946 am: a4a8a3545c

Original change: https://android-review.googlesource.com/c/platform/external/linux-kselftest/+/1670302

Change-Id: If363074c9f33a60bde60050f06ec667bcb36cd49