[OMPT] extend ompt tests by checks for frame pointers

OMPT tests can check for right frame information of tasks:
 * parent_task_frame was directly printed as a pointer, but actually points to a struct ompt_frame {void*, void*}
 * NULL is printed in the beginning of execution and loaded to FileChecker variable [[NULL]]
 * implicit tasks now also print their frame information
 * macro to print frame address from application
 * print task info for barrier begin

Patch by Joachim Protze!

Differential Revision: https://reviews.llvm.org/D23304

llvm-svn: 281463