first pass at internal sends. this is a very tentative work in progress, and it is possible that major changes may follow in the near future. it is certainly not complete, but the fundamental changes to Port/Buffer operation merit a commit at this point

git-svn-id: svn://localhost/ardour2/branches/3.0@4464 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/pbd/SConscript

@@ -54,6 +54,8 @@ xml++.cc
 conf = Configure(pbd)
 if conf.CheckFunc('getmntent'):
     conf.env.Append(CCFLAGS="-DHAVE_GETMNTENT")
+if conf.CheckCHeader('execinfo.h'):
+    conf.env.Append(CXXFLAGS="-DHAVE_EXECINFO")
 pbd = conf.Finish()
 
 pbd.Merge ([ libraries['sigc2'],