Revert "Don't pass $SHELL as argument to $SHELL in fallback profile"

See Pty.cpp for notes on why the arguments should not be empty.
This caused no harm, but this needs to be "fixed" throughout the
entire code.

This reverts commit d1c9b642.

src/Profile.cpp

@@ -149,7 +149,7 @@ FallbackProfile::FallbackProfile()
     // non-directory file name
     setProperty(Path, "FALLBACK/");
     setProperty(Command, qgetenv("SHELL"));
-    setProperty(Arguments, QStringList());
+    setProperty(Arguments, QStringList() << qgetenv("SHELL"));
     setProperty(Icon, "utilities-terminal");
     setProperty(Environment, QStringList() << QStringLiteral("TERM=xterm"));
     setProperty(LocalTabTitleFormat, "%d : %n");