Replace #if !WIN32 with #if HAVE_SYS_SOCKET_H and HAVE_SYS_IOCTL_H

(AIX needs sys/ioctl.h).  Reported by Michael Augustin
<maugustin-hi6Y0CQ0nG0@public.gmane.org>.

configure.in

@@ -225,7 +225,8 @@ AC_HELP_STRING([--disable-debug],[Disable debug options]),
 
 # Checks for header files.
 # AC_HEADER_STDC
-AC_CHECK_HEADERS([errno.h fcntl.h stdio.h stdlib.h unistd.h sys/uio.h sys/select.h])
+AC_CHECK_HEADERS([errno.h fcntl.h stdio.h stdlib.h unistd.h])
+AC_CHECK_HEADERS([sys/uio.h sys/select.h sys/socket.h sys/ioctl.h])
 AC_CHECK_FUNCS(poll gettimeofday select)
 
 # Checks for typedefs, structures, and compiler characteristics.

src/libssh2_priv.h

@@ -68,9 +68,11 @@
 
 #include <stdio.h>
 
-#ifndef WIN32
-#include <sys/socket.h>
-#include <sys/ioctl.h>
+#ifdef HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
+#endif
+#ifdef HAVE_SYS_IOCTL_H
+# include <sys/ioctl.h>
 #endif
 
 #ifdef LIBSSH2_LIBGCRYPT