GNU Make-isms in binutils/doc/Makefile.am

[John Marshall]

An OpenBSD-using colleague recently noted that the documentation makefile
uses $< in several explicit rules, which is a GNU Make extension:

  addr2line.1:    $(binutils_TEXI)
        touch $@
        -$(TEXI2POD) $(MANCONF) -Daddr2line < $< > addr2line.pod
        [...]                                 ^^

I haven't been following the list too closely for a while :-(, but I'm
guessing that you haven't decided to require GNU Make (and I can't find
anything to that effect in the archives or binutils/NEWS).

Happy to prepare a patch if appropriate and if you like, but it's pretty
trivial anyway.

    John