make "apt-get build-dep" installed packages marked automatic

by default. This can be changed by setting the value of
APT::Get::Build-Dep-Automatic to false (thanks to Aaron 
Haviland, closes: #44874, LP: #248268)

cmdline/apt-get.cc

@@ -2513,6 +2513,8 @@ bool DoBuildDep(CommandLine &CmdL)
             {
                // We successfully installed something; skip remaining alternatives
                skipAlternatives = hasAlternatives;
+	       if(_config->FindB("APT::Get::Build-Dep-Automatic", true) == true)
+		  Cache->MarkAuto(Pkg, true);
                continue;
             }
             else if (hasAlternatives)

debian/changelog

@@ -27,7 +27,11 @@ apt (0.7.15) UNRELEASED; urgency=low
   * document --install-recommends and --no-install-recommends
     (thanks to Dereck Wonnacott, LP: #126180)
   * fix various -Wall warnings
-
+  * make "apt-get build-dep" installed packages marked automatic
+    by default. This can be changed by setting the value of
+    APT::Get::Build-Dep-Automatic to false (thanks to Aaron 
+    Haviland, closes: #44874, LP: #248268)
+  
   [ Dereck Wonnacott ]
   * apt-ftparchive might write corrupt Release files (LP: #46439)
   * Apply --important option to apt-cache depends (LP: #16947) 

doc/examples/configure-index

@@ -54,6 +54,7 @@ APT
      Only-Source "";
      Diff-Only "false";
      Tar-Only "false";
+     Build-Dep-Automatic "true";
   };
 
   Cache