microblaze: Add missing implementation when !__ASSUME_TIME64_SYSCALLS

In commit a92f4e6299 ("linux: Add time64
pselect support"), a Microblaze specific implementation of
__pselect32() was added to cover the case of kernels < 3.15 which lack
the pselect6 system call.

This new file sysdeps/unix/sysv/linux/microblaze/pselect32.c takes
precedence over the default implementation
sysdeps/unix/sysv/linux/pselect32.c.

However sysdeps/unix/sysv/linux/pselect32.c provides an implementation
of __pselect32() which is needed when __ASSUME_TIME64_SYSCALLS is not
defined. On Microblaze, which is a 32-bit architecture,
__ASSUME_TIME64_SYSCALLS is only true for kernels >= 5.1.

Due to sysdeps/unix/sysv/linux/microblaze/pselect32.c taking
precedence over sysdeps/unix/sysv/linux/pselect32.c, it means that
when we are with a kernel >= 3.15 but < 5.1, we need a __pselect32()
implementation, but sysdeps/unix/sysv/linux/microblaze/pselect32.c
doesn't provide it, and sysdeps/unix/sysv/linux/pselect32.c which
would provide it is not compiled in.

This causes the following build failure on Microblaze with for example
Linux kernel headers 4.9:

[...]/build/libc_pic.os: in function `__pselect64':
(.text+0x120b44): undefined reference to `__pselect32'
collect2: error: ld returned 1 exit status

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

sysdeps/unix/sysv/linux/microblaze/pselect32.c

@@ -22,7 +22,9 @@
 #include <sys/poll.h>
 #include <sysdep-cancel.h>
 
-#ifndef __ASSUME_PSELECT
+#ifndef __ASSUME_TIME64_SYSCALL
+#include <sysdeps/unix/sysv/linux/pselect32.c>
+#elif !defined __ASSUME_PSELECT
 int
 __pselect32 (int nfds, fd_set *readfds, fd_set *writefds,
 	     fd_set *exceptfds, const struct __timespec64 *timeout,