integrated Eric Lavigne (sp???) contribution to build libxml2 on MacOS

* configure.in libxml.h parser.c testThreads.c macos/: integrated
  Eric Lavigne (sp???) contribution to build libxml2 on MacOS using
  CodeWarrior.
Daniel
diff --git a/testThreads.c b/testThreads.c
index 1c494ab..695bf2a 100644
--- a/testThreads.c
+++ b/testThreads.c
@@ -95,7 +95,7 @@
 
 	for (i = 0; i < num_threads; i++) {
 	    results[i] = NULL;
-	    tid[i] = -1;
+	    tid[i] = (pthread_t) -1;
 	}
 
 	for (i = 0; i < num_threads; i++) {