Fix linking on AIX with gcc.
diff --git a/configure b/configure
index aa872ec..c487270 100755
--- a/configure
+++ b/configure
@@ -252,6 +252,8 @@
                  shared_ext='.sl'
                  SHAREDLIB='libz.sl' ;;
          esac ;;
+  AIX*)
+        LDFLAGS="${LDFLAGS} -Wl,-brtl" ;;
   Darwin* | darwin* | *-darwin*)
              shared_ext='.dylib'
              SHAREDLIB=libz$shared_ext