malloc: Use __get_nprocs on arena_get2 (BZ 30945)

This restore the 2.33 semantic for arena_get2.  It was changed by
11a02b035b to avoid arena_get2 call malloc (back when __get_nproc
was refactored to use an scratch_buffer - 903bc7dcc2).  The
__get_nproc was refactored over then and now it also avoid to call
malloc.

The 11a02b035b did not take in consideration any performance
implication, which should have been discussed properly.  The
__get_nprocs_sched is still used as a fallback mechanism if procfs
and sysfs is not acessible.

Checked on x86_64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>

(cherry picked from commit 472894d2cf)

include/sys/sysinfo.h

@@ -14,10 +14,6 @@ libc_hidden_proto (__get_nprocs_conf)
 extern int __get_nprocs (void);
 libc_hidden_proto (__get_nprocs)
 
-/* Return the number of available processors which the process can
-   be scheduled.  */
-extern int __get_nprocs_sched (void) attribute_hidden;
-
 /* Return number of physical pages of memory in the system.  */
 extern long int __get_phys_pages (void);
 libc_hidden_proto (__get_phys_pages)

malloc/arena.c

@@ -820,7 +820,7 @@ arena_get2 (size_t size, mstate avoid_arena)
             narenas_limit = mp_.arena_max;
           else if (narenas > mp_.arena_test)
             {
-              int n = __get_nprocs_sched ();
+              int n = __get_nprocs ();
 
               if (n >= 1)
                 narenas_limit = NARENAS_FROM_NCORES (n);

misc/getsysstats.c

@@ -44,12 +44,6 @@ weak_alias (__get_nprocs, get_nprocs)
 link_warning (get_nprocs, "warning: get_nprocs will always return 1")
 
 
-int
-__get_nprocs_sched (void)
-{
-  return 1;
-}
-
 long int
 __get_phys_pages (void)
 {

sysdeps/mach/getsysstats.c

@@ -62,12 +62,6 @@ __get_nprocs (void)
 libc_hidden_def (__get_nprocs)
 weak_alias (__get_nprocs, get_nprocs)
 
-int
-__get_nprocs_sched (void)
-{
-  return __get_nprocs ();
-}
-
 /* Return the number of physical pages on the system. */
 long int
 __get_phys_pages (void)

sysdeps/unix/sysv/linux/getsysstats.c

@@ -29,7 +29,7 @@
 #include <sys/sysinfo.h>
 #include <sysdep.h>
 
-int
+static int
 __get_nprocs_sched (void)
 {
   enum