perf annotate: Check null of sym pointer before using it
perf annotate: Check null of sym pointer before using it

Sym may be NULL, and that will cause perf to crash.

Signed-off-by: Shan Wei <49fd333a353791bf0142525ef4715c0206e6c8ea@tencent.com>
Cc: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@redhat.com>
Cc: Namhyung Kim <1b20bcb62cf1b100c528e605608922000dc2fc80@lge.com>
Cc: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>
Cc: Peter Zijlstra <645ca7d3a8d3d4f60557176cd361ea8351edc32b@chello.nl>
Link: 9c9ce41fb252283b71f43666199a32b344b7fd9a@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <293abb6b76d7791c0732cc517d38c4b5c734b87f@redhat.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs