Delete bfd_my_archive macro

Delete bfd_my_archive macro

Many more places use abfd->my_archive rather than bfd_my_archive (abfd),
so let's make the code consistently use the first idiom.

bfd/
	* bfd-in.h (bfd_my_archive): Delete.
	* bfd-in2.h: Regenerate.
binutils/
	* ar.c: Expand uses of bfd_my_archive.
	* size.c: Likewise.
ld/
	* ldlang.c: Expand uses of bfd_my_archive.
	* ldmain.c: Likewise.
	* ldmisc.c: Likewise.
	* plugin.c: Likewise.