qt,cpp: Consistently use nullptr and override

* lang/cpp/src/Makefile.am, lang/qt/src/Makefile.am (AM_CPPFLAGS):
Add suggest-override and zero-as-null-pointer-constant warnings.

* lang/cpp/src/*, lang/qt/src/*: Consistenly use nullptr and override.

--
This was especially important for the headers so that downstream
users of GpgME++ or QGpgME do not get flooded by warnings if
they have these warnings enabled.

It also improves compiler errors/warnings in case of accidental
mistakes.

1 files changed, 2 insertions, 2 deletions

diff --git a/lang/cpp/src/gpgsetexpirytimeeditinteractor.cpp b/lang/cpp/src/gpgsetexpirytimeeditinteractor.cpp
index 7aebe73a..2936d194 100644
--- a/lang/cpp/src/gpgsetexpirytimeeditinteractor.cpp
+++ b/lang/cpp/src/gpgsetexpirytimeeditinteractor.cpp
@@ -81,10 +81,10 @@ const char *GpgSetExpiryTimeEditInteractor::action(Error &err) const
         return "Y";
     case START:
     case ERROR:
-        return 0;
+        return nullptr;
     default:
         err = Error::fromCode(GPG_ERR_GENERAL);
-        return 0;
+        return nullptr;
     }
 }