MFC r210344,r210345,r210348.

MFC r210344,r210345,r210348.

r210344:
  Avoid switching between "unsigned char" and "char" in the C code
  generated from "libelf_convert.m4".

r210345:
  * Deprecate `elf_getshnum()`, `elf_getphnum()` and `elf_getshstrndx()` in
    favour of `elf_getshdrnum()`, `elf_getphdrnum()` and `elf_getshdrstrndx()`
    respectively.
  * Add new manual pages for `elf_getshdrstrndx()`, `elf_getphdrnum()` and
    `elf_getshdrnum()`.
  * Add a deprecation warning for `elf_getshstrndx()`, `elf_getphnum()` and
    `elf_getshnum()`.

r210348:
  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".

git-svn-id: svn://svn.freebsd.org/base/stable/8@212204 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f