Fix build with Bionic libc

Fix build with Bionic libc

Add generic tests for fopen64 and fputs_unlocked functions to fix build
with Bionic libc that does not provide them.

* configure.ac (AC_CHECK_FUNCS): Add fopen64 and fputs_unlocked.
* strace.c [_LARGEFILE64_SOURCE]: Use fopen instead of fopen64
if !HAVE_FOPEN64.
Use fputs instead of fputs_unlocked if !HAVE_FPUTS_UNLOCKED.
* vsprintf.c: Use fputs instead of fputs_unlocked
if !HAVE_FPUTS_UNLOCKED.

Reported-by: Elliott Hughes <enh@google.com>