applied Serguei Narojnyi's patch to add native thread support on the Win32

* threads.c: applied Serguei Narojnyi's patch to add native
  thread support on the Win32 platform
* testThreadsWin32.c Makefile.am: added the test program also
  from Serguei, Win32 specific
* include/win32config.h include/libxml/xmlwin32version.h.in:
  added patch from Igor for the Windows thread specific defines.
Daniel

testThreadsWin32.c

@@ -0,0 +1,146 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include "libxml.h"
+
+#if defined(LIBXML_THREAD_ENABLED) && defined(LIBXML_CATALOG_ENABLED)
+#include <libxml/globals.h>
+#include <libxml/threads.h>
+#include <libxml/parser.h>
+#include <libxml/catalog.h>
+#include <windows.h>
+#include <string.h>
+#include <assert.h>
+
+#define	MAX_ARGC	20
+#define TEST_REPEAT_COUNT 500
+
+static HANDLE tid[MAX_ARGC];
+
+static const char *catalog = "test/threads/complex.xml";
+static char *testfiles[] = {
+    "test/threads/abc.xml",
+    "test/threads/acb.xml",
+    "test/threads/bac.xml",
+    "test/threads/bca.xml",
+    "test/threads/cab.xml",
+    "test/threads/cba.xml",
+    "test/threads/invalid.xml",
+};
+
+const char *Okay = "OK";
+const char *Failed = "Failed";
+
+#ifndef xmlDoValidityCheckingDefaultValue
+#error xmlDoValidityCheckingDefaultValue is not a macro
+#endif
+#ifndef xmlGenericErrorContext
+#error xmlGenericErrorContext is not a macro
+#endif
+
+static DWORD WINAPI
+thread_specific_data(void *private_data)
+{
+    xmlDocPtr myDoc;
+    const char *filename = (const char *) private_data;
+    int okay = 1;
+
+    if (!strcmp(filename, "test/threads/invalid.xml")) {
+        xmlDoValidityCheckingDefaultValue = 0;
+        xmlGenericErrorContext = stdout;
+    } else {
+        xmlDoValidityCheckingDefaultValue = 1;
+        xmlGenericErrorContext = stderr;
+    }
+    myDoc = xmlParseFile(filename);
+    if (myDoc) {
+        xmlFreeDoc(myDoc);
+    } else {
+        printf("parse failed\n");
+	okay = 0;
+    }
+    if (!strcmp(filename, "test/threads/invalid.xml")) {
+        if (xmlDoValidityCheckingDefaultValue != 0) {
+	    printf("ValidityCheckingDefaultValue override failed\n");
+	    okay = 0;
+	}
+        if (xmlGenericErrorContext != stdout) {
+	    printf("xmlGenericErrorContext override failed\n");
+	    okay = 0;
+	}
+    } else {
+        if (xmlDoValidityCheckingDefaultValue != 1) {
+	    printf("ValidityCheckingDefaultValue override failed\n");
+	    okay = 0;
+	}
+        if (xmlGenericErrorContext != stderr) {
+	    printf("xmlGenericErrorContext override failed\n");
+	    okay = 0;
+	}
+    }
+    if (okay == 0)
+	return ((DWORD) Failed);
+    return ((DWORD) Okay);
+}
+
+int
+main()
+{
+	unsigned int i, repeat;
+	unsigned int num_threads = sizeof(testfiles) / sizeof(testfiles[0]);
+	DWORD results[MAX_ARGC];
+	BOOL ret;
+
+	xmlInitParser();
+	for (repeat = 0;repeat < TEST_REPEAT_COUNT;repeat++)
+	{
+		xmlLoadCatalog(catalog);
+
+		for (i = 0; i < num_threads; i++)
+		{
+			results[i] = 0;
+			tid[i] = (HANDLE) -1;
+		}
+
+		for (i = 0; i < num_threads; i++)
+		{
+			DWORD useless;
+			tid[i] = CreateThread (NULL, 0, thread_specific_data, testfiles[i], 0, &useless);
+			if (tid[i] == NULL)
+			{
+				perror("CreateThread");
+				exit(1);
+			}
+		}
+
+		if (WaitForMultipleObjects (num_threads, tid, TRUE, INFINITE) == WAIT_FAILED) perror ("WaitForMultipleObjects failed");
+
+		for (i = 0; i < num_threads; i++)
+		{
+			ret = GetExitCodeThread (tid[i], &results[i]);
+			if (ret == 0)
+			{
+				perror("GetExitCodeThread");
+				exit(1);
+			}
+			CloseHandle (tid[i]);
+		}
+
+		xmlCatalogCleanup();
+		for (i = 0; i < num_threads; i++)
+			if (results[i] != (DWORD) Okay) printf("Thread %d handling %s failed\n", i, testfiles[i]);
+	}
+
+	xmlCleanupParser();
+	xmlMemoryDump();
+
+	return (0);
+}
+
+#else /* !LIBXML_THREADS_ENABLED */
+int
+main()
+{
+    fprintf(stderr, "libxml was not compiled with thread or catalog support\n");
+    return (0);
+}
+#endif