Moved autotests in category 'testlib' into new directory structure

Task-number: QTBUG-21353

Change-Id: I2e2ad4b7570f80b3e6500821f769e967f0a75027
Reviewed-on: http://codereview.qt-project.org/4438
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>

tests/auto/auto.pro

@@ -6,7 +6,8 @@ SUBDIRS += \
     network.pro \
     sql \
     xml \
-    other
+    testlib \
+    other \
 
 !cross_compile:                             SUBDIRS += host.pro
 contains(QT_CONFIG, opengl):                SUBDIRS += opengl

tests/auto/corelib.pro

@@ -4,6 +4,4 @@ SUBDIRS=\
    collections \
    exceptionsafety \
    qobjectrace \
-   qsignalspy \
-   selftests \
    utf8