new stacktrace function in libpbd3; variable size GUI request thread queues

git-svn-id: svn://localhost/trunk/ardour2@330 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/pbd3/SConscript

@@ -18,6 +18,7 @@ pathscanner.cc
 pool.cc
 pthread_utils.cc
 receiver.cc
+stacktrace.cc
 strsplit.cc
 textreceiver.cc
 transmitter.cc
@@ -31,6 +32,8 @@ xml++.cc
 conf = Configure(pbd3)
 if conf.CheckFunc('getmntent'):
     conf.env.Append(CCFLAGS="-DHAVE_GETMNTENT")
+if conf.CheckCHeader('execinfo.h'):
+    conf.env.Append(CXXFLAGS="-DHAVE_EXECINFO")
 pbd3 = conf.Finish()
 
 pbd3.Merge ([ libraries['sigc2'], libraries['xml'] ])