[llvm-opt-report] Fix context-sensitive lines where nothing happened

Don't print a line multiple times, each for different inlining contexts, if
nothing happened in any context. This prevents situations like this:

 [[
  > main:
 65     |       if ((i * ni + j) % 20 == 0) fprintf
  > print_array:
 65     |       if ((i * ni + j) % 20 == 0) fprintf
 ]]

which could happen if different optimizations were missed in different inlining
contexts.

llvm-svn: 291361