>From Solaris 10 it's not necessary to link explicitly with libpthread
library because all the threading functions are in the libc library.

--- libxml2-2.9.0/configure.in	Wed Jan 30 07:40:27 2013
+++ libxml2-2.9.0/configure.in	Wed Jan 30 07:45:50 2013
@@ -1014,6 +1014,15 @@
 	       fi
 	   fi
        ;;
+       solaris*)
+           SOLARIS_MAJOR=`echo $host_os | sed -e 's+solaris++' -e 's+\..*++'`
+           SOLARIS_MINOR=`echo $host_os | sed 's+solaris[[0-9]]*\.++'`
+           if test $SOLARIS_MAJOR -eq 2 -a $SOLARIS_MINOR -ge 10 -o \
+                   $SOLARIS_MAJOR -gt 2 ; then
+ 	       THREAD_LIBS=""
+	       BASE_THREAD_LIBS=""
+           fi
+       ;;
     esac
     if test "$WITH_THREADS" = "1" ; then
 	THREAD_CFLAGS="$THREAD_CFLAGS -D_REENTRANT"