fix startup errors with 2.x related to boost linkage on some platforms

Note: this should not be required because we do not actually link with ANY boost libraries, so the
occurence of this bug in ardour at run time indicates that the wrong version of boost was used and/or
incorrect flags for using boost are in use.

Fix from  David Henningsson <david.henningsson@canonical.com>

libs/surfaces/generic_midi/SConscript

@@ -42,7 +42,8 @@ genericmidi.Merge ([
 	libraries['usb'],
 	libraries['xml'],
 	libraries['glib2'],
-	libraries['glibmm2']
+	libraries['glibmm2'],
+	libraries['boost']
 	])
 
 libardour_genericmidi = genericmidi.SharedLibrary('ardour_genericmidi', genericmidi_files)

libs/surfaces/tranzport/SConscript

@@ -63,6 +63,7 @@ tranzport.Merge ([
     libraries['xml'],
     libraries['glib2'],
     libraries['glibmm2'],
+    libraries['boost'],
     libraries['usb'],
     libraries['sndfile']
     ])