Rename bits/linkmap.h to linkmap.h (bug 14912).

It was noted in
<https://sourceware.org/ml/libc-alpha/2012-09/msg00305.html> that the
bits/*.h naming scheme should only be used for installed headers.
This patch renames bits/linkmap.h to plain linkmap.h to follow that
convention.

Tested for x86_64 (testsuite, and that installed stripped shared
libraries are unchanged by the patch).

	[BZ #14912]
	* bits/linkmap.h: Move to ...
	* sysdeps/generic/linkmap.h: ...here.
	* sysdeps/aarch64/bits/linkmap.h: Move to ...
	* sysdeps/aarch64/linkmap.h: ...here.
	* sysdeps/arm/bits/linkmap.h: Move to ...
	* sysdeps/arm/linkmap.h: ...here.
	* sysdeps/hppa/bits/linkmap.h: Move to ...
	* sysdeps/hppa/linkmap.h: ...here.
	* sysdeps/ia64/bits/linkmap.h: Move to ...
	* sysdeps/ia64/linkmap.h: ...here.
	* sysdeps/mips/bits/linkmap.h: Move to ...
	* sysdeps/mips/linkmap.h: ...here.
	* sysdeps/s390/bits/linkmap.h: Move to ...
	* sysdeps/s390/linkmap.h: ...here.
	* sysdeps/sh/bits/linkmap.h: Move to ...
	* sysdeps/sh/linkmap.h: ...here.
	* sysdeps/x86/bits/linkmap.h: Move to ...
	* sysdeps/x86/linkmap.h: ...here.
	* include/link.h: Include <linkmap.h> instead of <bits/linkmap.h>.