Fix NULL pointer dereference.
Fix NULL pointer dereference.

Bug: 13120542

(cherry picked from commit e6c23a7dbafa4c93c661053e6c34ae0725e38313)

Change-Id: I62e1a639a3252016e1a57b9243784d8c6fa21713

androidarmv6/android_external_libunwind,frida/libunwind,androidarmv6/android_external_libunwind,geekboxzone/mmallow_external_libunwind,geekboxzone/lollipop_external_libunwind,zeldin/platform_external_libunwind,frida/libunwind,frida/libunwind,SyndicateRogue/libunwind,CyanogenMod/android_external_libunwind,zeldin/platform_external_libunwind,geekboxzone/mmallow_external_libunwind,androidarmv6/android_external_libunwind,android-ia/platform_external_libunwind,CyanogenMod/android_external_libunwind,zeldin/platform_external_libunwind,SyndicateRogue/libunwind,geekboxzone/lollipop_external_libunwind,android-ia/platform_external_libunwind,geekboxzone/lollipop_external_libunwind,SyndicateRogue/libunwind,geekboxzone/mmallow_external_libunwind,android-ia/platform_external_libunwind,CyanogenMod/android_external_libunwind