Patch fixes build on hurd-i386, kfreebsd-i386 and kfreebsd-amd64
architectures.

--- tclthread-2.6.7.orig/configure
+++ tclthread-2.6.7/configure
@@ -8289,7 +8289,7 @@
 fi
 
 	    ;;
-	Linux*)
+	Linux*|GNU*)
 	    SHLIB_CFLAGS="-fPIC"
 	    SHLIB_SUFFIX=".so"