Allow to set a qt.conf from the outside using the environment. This allows
to inject new prefixes and other paths into qmake. This is needed when using
the same qmake binary to build qt/x11 and qt/embedded

Index: qtopia-core-opensource-src-4.3.3/src/corelib/global/qlibraryinfo.cpp
===================================================================
--- qtopia-core-opensource-src-4.3.3.orig/src/corelib/global/qlibraryinfo.cpp	2007-12-25 00:55:32.000000000 +0100
+++ qtopia-core-opensource-src-4.3.3/src/corelib/global/qlibraryinfo.cpp	2007-12-25 01:20:18.000000000 +0100
@@ -42,6 +42,7 @@
 #include "qpointer.h"
 #ifdef QT_BUILD_QMAKE
 extern QString qmake_libraryInfoFile();
+#include <stdlib.h>
 #else
 # include "qcoreapplication.h"
 #endif
@@ -107,6 +108,10 @@
 #ifdef QT_BUILD_QMAKE
     if(!QFile::exists(qtconfig))
         qtconfig = qmake_libraryInfoFile();
+    if (!QFile::exists(qtconfig)) {
+        QByteArray config = getenv("QT_CONF_PATH");
+        qtconfig = config;
+    }
 #else
     if (!QFile::exists(qtconfig) && QCoreApplication::instance()) {
 #ifdef Q_OS_MAC