Replace use of putenv in test case

This should be using qputenv; putenv is deprecated on MSVC.

Change-Id: I7c27cf5f7955624fa3553b7a34ab11c6fae462b8
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>

tests/auto/corelib/codecs/qtextcodec/echo/main.cpp

@@ -47,8 +47,7 @@
 
 int main(int argc, char **argv)
 {
-    static char lc_all[] = "LC_ALL=C";
-    putenv(lc_all);
+    qputenv("LC_ALL", "C");
     QCoreApplication app(argc, argv);
 
     QString string(QChar(0x410));