We goofed a little when we overrode the DBX_FUNCTION_FIRST logic so that
we could control the use of dbxout_really_begin_function() based on if the
target format is a.out or ELF. The goof resulted in our target logic never
being used and thus we always called dbxout_really_begin_function() twice
in the ELF case and never in the a.out case.

PR: 41671
Submitted by: Mark Kettenis <kettenis@gnu.org>