CppTools: Fix qbs build.

Change-Id: I3dc1bc8845ee26a1f8a2c8264c9dc2eaa0aa1896
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

src/plugins/cpptools/cpptools.qbs

@@ -66,6 +66,8 @@ QtcPlugin {
         "cpphighlightingsupport.h",
         "cpphighlightingsupportinternal.cpp",
         "cpphighlightingsupportinternal.h",
+        "cppindexingsupport.cpp",
+        "cppindexingsupport.h",
         "cpplocalsymbols.cpp",
         "cpplocalsymbols.h",
         "cpplocatorfilter.cpp",