[llvm-cov] Add the "Go to first unexecuted line" feature.

This patch provides easy navigation to find the zero count lines, especially useful when the source file is very large.

Differential Revision: https://reviews.llvm.org/D23277


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280739 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed