[sanitizer_common] Rename OnPrint to __sanitizer_on_print.

Summary:
https://reviews.llvm.org/D28596 exposed OnPrint in the global namespace,
which can cause collisions with user-defined OnPrint() functions.

Reviewers: vitalybuka, dvyukov

Reviewed By: vitalybuka, dvyukov

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67987

llvm-svn: 373518