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>
diff --git a/vsprintf.c b/vsprintf.c
index 92fe1a7..0125e72 100644
--- a/vsprintf.c
+++ b/vsprintf.c
@@ -16,6 +16,10 @@
 #include <stdarg.h>
 #include <limits.h>
 
+#ifndef HAVE_FPUTS_UNLOCKED
+# define fputs_unlocked fputs
+#endif
+
 #define noinline_for_stack /*nothing*/
 #define likely(expr)       (expr)
 #define unlikely(expr)     (expr)