Symlink required binutils/BFD headers to local dir

Symlink required binutils/BFD headers to local dir

... to minimize the chance of clashes with system headers.

Also, remove the -lcygwin from Makefile.in: this breaks canadian
build on cygwin, as it tries to pass -lcygwin into non-Cygwin host
CC. This chunk pre-dates the addition of -lc into configure.ac and
passing -lc should be sufficient (it works for me).

Signed-off-by: Alexey Neyman <stilor@att.net>