Clang: Ignore certain warnings in header files

We already had this workarounded, but it got lost in the refactorings.

Task-number: QTCREATORBUG-12067
Change-Id: Ie01f9d41f25d17d1b595204748634bc87ef44378
Reviewed-by: Marco Bubke <marco.bubke@theqtcompany.com>
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/plugins/cpptools/cpptoolsunittestfiles.pri

@@ -4,6 +4,10 @@ contains(CONFIG, dll) {
     DEFINES += CPPTOOLS_STATIC_LIBRARY
 }
 
-HEADERS += $$PWD/senddocumenttracker.h
+HEADERS += \
+    $$PWD/cppprojectfile.h \
+    $$PWD/senddocumenttracker.h \
 
-SOURCES += $$PWD/senddocumenttracker.cpp
+SOURCES += \
+    $$PWD/cppprojectfile.cpp \
+    $$PWD/senddocumenttracker.cpp