dtmail: resolve coverity warnings related to uninitialised members in C++ classes

cde/programs/dtmail/libDtMail/Common/DtMailError.C

@@ -397,6 +397,7 @@ DtMailEnv::DtMailEnv()
   _client = NULL;
   _implClearFunc = NULL;
   _fatal = DTM_FALSE;
+  _error_minor_code = DTME_NoError;
 }
 
 #ifdef hpV4

cde/programs/dtmail/libDtMail/Common/DtMailMailBox.C

@@ -68,6 +68,8 @@ DtMail::MailBox::MailBox(DtMailEnv & error,
     _callback = cb;
     _cb_data = clientData;
     _obj_mutex = MutexInit();
+    _mail_box_writable = DTM_FALSE;
+    _default_mode = 0;
 }
 
 DtMail::MailBox::~MailBox(void)

cde/programs/dtmail/libDtMail/Common/Threads.C

@@ -246,8 +246,11 @@ Condition::Condition(void)
 #if defined(POSIX_THREADS)
     _condition = malloc(sizeof(cond_t));
     cond_init((cond_t *)_condition, USYNC_THREAD, NULL);
+#else
+    _condition = NULL;
 #endif
 
+    _state = 0;
 }
 
 Condition::~Condition(void)