[tests] Avoid warning from ignoring system() return value. MER#1749

Compiler warns about ignoring system() function return value.

Since this is test/debug code, just change the code enough to silence the
warning and make it clear we are ignoring the return value on purpose.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

tests/powermanagement/powermanagementtests/helpslot.h

@@ -52,7 +52,11 @@ class HelpSlot : public QThread
         {
             while(!m_stop) {
                 msleep(250);
-                system(QString("echo 0 0 0 | datafaker %1 & { sleep 0.1; eval 'kill $!' &> /dev/null; }").arg(m_inputFile).toLatin1().constData());
+                if (system(QString("echo 0 0 0 | datafaker %1 & { sleep 0.1; eval 'kill $!' &> /dev/null; }").arg(m_inputFile).toLatin1().constData()) != 0) {
+                    /* Gcc will complain about completely ignoring
+                     * system() return values. As we really do not
+                     * care here, use dummy test to silence warnings. */
+                }
             }
         }
     }

tests/powermanagement/standbyoverridetests/helpslot.h

@@ -52,11 +52,15 @@ class HelpSlot : public QThread
         {
             while(!m_stop) {
                 msleep(250);
-                system(QString("echo 0 0 0 | datafaker %1 & { sleep 0.1; eval 'kill $!' &> /dev/null; }").arg(m_inputFile).toLatin1().constData());
+                if (system(QString("echo 0 0 0 | datafaker %1 & { sleep 0.1; eval 'kill $!' &> /dev/null; }").arg(m_inputFile).toLatin1().constData()) != 0) {
+                    /* Gcc will complain about completely ignoring
+                     * system() return values. As we really do not
+                     * care here, use dummy test to silence warnings. */
+                }
             }
-
         }
     }
+
     QString m_inputFile;
     int m_valueCount;
     bool m_stop;