[OPENMP] Enable correct generation of runtime call when target directive is...

[OPENMP] Enable correct generation of runtime call when target directive is separated from teams directive by multiple curly brackets

http://reviews.llvm.org/D18474

This patch fixes a bug in code generation of the correct OpenMP runtime library call in presence of target and teams, when target is separated by teams with multiple curly brackets. The current implementation will not be able to see the teams directive inside target and issue a call to tgt_target instead of the correct one tgt_target_teams.

llvm-svn: 267972