Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Move helper functions `_libelf_ar_get_{name,number,string}()` and
`_libelf_ar_open()` to a new compilation unit "libelf_ar_util.c"
to break the circular dependency between "elf_memory.o" and
"libelf_ar.o".

Obtained from: elftoolchain
MFC after: 1 month

Perform additional checks when translating between file and memory
representations of ELF types.

The ELF(3) API allows applications to request a conversion that is
`in-place', i.e., with source and destinations data buffers being
the same. However, the file and memory sizes of ELF sections that
have additional internal structure, such as those of type `Elf_Note',
or `Elf_GNU_Hash_Header', can be determined only known after the
type-specific headers that comprise the first few words in these
sections are read and translated.

Pass in the size of destination buffer to type translation routines
in "libelf_convert.m4" and have these routines return an error code
if the translated data would not fit inside the destination buffer.

Obtained from: elftoolchain
MFC after: 1 month

Allow an application that updates only the ELF Ehdr to work.

Obtained from: elftoolchain
MFC after: 1 month

Keep shadow copies of the `e_shnum', `e_phnum' and `e_shstrndx'
members of the ELF Executable Header inside the library-private
`struct _Elf' descriptor and only update the underlying Elf{32,64}_Ehdr
structure on an elf_update(3) call. These fields of the Ehdr
structure are technically `out of bounds' for an application program
per the ELF(3) API, but we've seen applications that initialize
a new Ehdr structure using memcpy(), messing up the library's
invariants. [1]

Implement elf_getphnum() and handle ELF objects with more than
64K program header table entries.

Reported by: jb [1]

MFP4: Add an implementation of the ELF(3) and GELF(3) API set.

Bump __FreeBSD_version.

Reviewed by: jb