On AIX, use $config{ptr_size} to conditionally add 32 bit linker flags.

This eliminates the only use of $config{arch_bits} and hence the only use of
build::probe::numbits().

Only set this flag if the linker is xlc - gcc doesn't support it.

Configure.pl

@@ -555,16 +555,15 @@ sub uniq {
                         . "\t\$(CP) 3rdparty/msinttypes/*.h \"\$(DESTDIR)\$(PREFIX)/include/msinttypes\"\n";
 }
 
+if ($^O eq 'aix' && $config{ld} =~ /xlc/ && $config{ptr_size} == 4) {
+    $config{ldflags} = join(',', $config{ldflags}, '-bmaxdata:0x80000000');
+}
+
 build::probe::C_type_bool(\%config, \%defaults);
 build::probe::computed_goto(\%config, \%defaults);
 build::probe::pthread_yield(\%config, \%defaults);
 build::probe::pthread_setname_np(\%config, \%defaults);
 build::probe::check_fn_malloc_trim(\%config, \%defaults);
-if ($^O eq 'aix') {
-    build::probe::numbits(\%config, \%defaults);
-    $config{ldflags} = join(',', $config{ldflags}, '-bmaxdata:0x80000000')
-        if $config{arch_bits} == 32;
-}
 build::probe::rdtscp(\%config, \%defaults);
 
 my $order = $config{be} ? 'big endian' : 'little endian';

build/probe.pm

@@ -756,39 +756,6 @@ EOT
     $config->{has_pthread_setname_np} = $has_pthread_setname_np || 0
 }
 
-sub numbits {
-    my ($config) = @_;
-    my $restore = _to_probe_dir();
-    _spew('numbits.c', <<'EOT');
-#include <stdint.h>
-
-int main(int argc, char **argv) {
-#if UINTPTR_MAX == 0xffffffff
-return 32;
-/* 32-bit */
-#elif UINTPTR_MAX == 0xffffffffffffffff
-/* 64-bit */
-return 64;
-#else
-/* unknown */
-return -1;
-#endif
-}
-EOT
-
-    print ::dots('    probing number of bits');
-    my $print_result;
-    my $num_bits = 0;
-    if(compile($config, 'numbits')) {
-        $num_bits = $print_result = system('./numbits') >> 8;
-    }
-    if (!defined $print_result || $print_result == -1) {
-        $print_result = 'UNKNOWN';
-    }
-    print $print_result . "\n";
-    $config->{arch_bits} = $num_bits;
-}
-
 sub win32_compiler_toolchain {
     my ($config) = @_;
     my $has_nmake = 0 == system('nmake /? >NUL 2>&1');