testlib: Add missing header files to .pro file

With all the headers missing, Creator's clang code model just gives up and
it's impossible to work on testlib in Creator.

Change-Id: I8814264db10992eeec6f45625580f6788d23b56b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/testlib/testlib.pro

@@ -12,6 +12,7 @@ unix:!embedded:QMAKE_PKGCONFIG_DESCRIPTION = Qt \
 QMAKE_DOCS = $$PWD/doc/qttestlib.qdocconf
 
 HEADERS = \
+    qabstracttestlogger_p.h \
     qbenchmark.h \
     qbenchmark_p.h \
     qbenchmarkmeasurement_p.h \
@@ -21,10 +22,16 @@ HEADERS = \
     qbenchmarkperfevents_p.h \
     qbenchmarkmetric.h \
     qbenchmarkmetric_p.h \
+    qcsvbenchmarklogger_p.h \
+    qplaintestlogger_p.h \
+    qsignaldumper_p.h \
     qsignalspy.h \
+    qteamcitylogger_p.h \
     qtestaccessible.h \
     qtestassert.h \
     qtestcase.h \
+    qtestcoreelement_p.h \
+    qtestcorelist_p.h \
     qtestdata.h \
     qtestevent.h \
     qtesteventloop.h \
@@ -32,15 +39,23 @@ HEADERS = \
     qtest_network.h \
     qtest_widgets.h \
     qtest.h \
+    qtestelement_p.h \
+    qtestelementattribute_p.h \
     qtestkeyboard.h \
+    qtestlog_p.h \
     qtestmouse.h \
+    qtestresult_p.h \
     qtestspontaneevent.h \
     qtestsystem.h \
+    qtesttable_p.h \
     qtesttouch.h \
     qtestblacklist_p.h \
     qtesthelpers_p.h \
     qttestglobal.h \
-    qtaptestlogger_p.h
+    qtestxunitstreamer_p.h \
+    qtaptestlogger_p.h \
+    qxmltestlogger_p.h \
+    qxunittestlogger_p.h
 
 SOURCES = \
     qtestcase.cpp \