syscall: Make common implementation match unistd.h

The definition of syscall() in unistd.h is with varargs.  Traditionally
the common implementation in uclibc has been with regular arguments.
This patch updates that by using varargs.

This has caused issues on architectures like or1k which have different
calling conventions for varargs and regular arg parameters.

The implementation here is based on an implementation from Joel Stanley
<joel@jms.id.au>.  There is a difference that I do not initialize the
stack args with 0 as they are immediately overwritten by va_args.

Signed-off-by: Stafford Horne <shorne@gmail.com>

libc/sysdeps/linux/common/syscall.c

@@ -4,9 +4,25 @@
  * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
  */
 
+#include <stdarg.h>
 #include <sys/syscall.h>
+#include <unistd.h>
 
-long syscall(long sysnum, long arg1, long arg2, long arg3, long arg4, long arg5, long arg6)
+long syscall(long sysnum, ...)
 {
+
+	unsigned long arg1, arg2, arg3, arg4, arg5, arg6;
+	va_list arg;
+
+	va_start (arg, sysnum);
+	arg1 = va_arg (arg, unsigned long);
+	arg2 = va_arg (arg, unsigned long);
+	arg3 = va_arg (arg, unsigned long);
+	arg4 = va_arg (arg, unsigned long);
+	arg5 = va_arg (arg, unsigned long);
+	arg6 = va_arg (arg, unsigned long);
+	va_end (arg);
+
+        __asm__ volatile ( "" ::: "memory" );
 	return INLINE_SYSCALL_NCS(sysnum, 6, arg1, arg2, arg3, arg4, arg5, arg6);
 }