Produces a subset of the standard
that shows only those functions that call, or are called by, the
functions given as arguments to this linker option.
The callgraph file:
Is saved in the same directory as the generated image.
Has the same name as the linked image. Use the
--callgraph_file=option to specify a different callgraph filename.
Has a default output format of HTML. Use the
--callgraph_output=option to control the output format.