Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r270882, r270930:

In ARM asm code, ensure that every ENTRY(foo) has a matching END(foo).
The EABI unwind info requires a .fnend for every .fnstart, and newer
binutils will complain about seeing two .fnstart in a row. This change
allows newer tools to compile our code.

Do not generate unwind info in asm functions if _STANDALONE is defined.
The .fnend op causes the assembler to emit RELOC references to unwind
support functions that don't exist in libstand.

Approved by: re(gjb)

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Teach siglongjmp about the VFP version of the setjmp buffer.

This fixes a bug where a call to sigsetjmp followed by siglongjmp may fail
when run on a machine with VFP enabled.

Include machine/setjmp.h to get the definition of _JB_MAGIC__SETJMP. This
allows us to remove it from the ARM copy of machine/asm.h.

Add a week alias __siglongjmp => siglongjmp.

Import the FreeBSD/arm libc bits.

Obtained from: NetBSD