Fixes: remove use of qttest_p4.prf

    Details:  makes it compile now with Qt snapshots

tests/auto/cplusplus/ast/ast.pro

-load(qttest_p4)
+TEMPLATE = app
+CONFIG += qt warn_on console depend_includepath
+QT = core testlib
 include(../shared/shared.pri)
-QT = core
 SOURCES += tst_ast.cpp

tests/auto/cplusplus/semantic/semantic.pro

-load(qttest_p4)
+TEMPLATE = app
+CONFIG += qt warn_on console depend_includepath
+QT = core testlib
 include(../shared/shared.pri)
-QT = core
 
 SOURCES += tst_semantic.cpp