add missing errno.h include

it was masked by the precompiled header

Change-Id: I9ba7b0faa716cfa6844b9a9f81fa2a3aa67f5da4
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>

tools/configure/environment.cpp

@@ -42,6 +42,7 @@
 #include "environment.h"
 
 #include <process.h>
+#include <errno.h>
 #include <iostream>
 #include <qdebug.h>
 #include <QDir>