bfd: Rename real_{ftell, fseek, fopen}

bfd: Rename real_{ftell, fseek, fopen}

Give these bfd-internal symbols with external linkage a _bfd_ prefix
to avoid collisions in the global symbol namespace.

bfd/ChangeLog:
2017-02-17  Pedro Alves  <palves@redhat.com>

	* bfdio.c (real_ftell): Rename to ...
	(_bfd_real_ftell): ... this.
	(real_fseek): Rename to ...
	(_bfd_real_fseek): ... this.
	(real_fopen): Rename to ...
	(_bfd_real_fopen): ... this.
	* libbfd-in.h (real_ftell): Rename to ...
	(_bfd_real_ftell): ... this.
	(real_fseek): Rename to ...
	(_bfd_real_fseek): ... this.
	(real_fopen): Rename to ...
	(_bfd_real_fopen): ... this.
	* cache.c, dwarf2.c, opncls.c: Adjust all callers.
	* libbfd.h: Regenerate.