Support builds with no package output

This feature adds support for buildfiles which include a build()
function but produces no package output (no files installed in $PKG).

src/buildfile.cc

@@ -43,6 +43,7 @@ CBuildFile::CBuildFile(string filename)
 {
    CBuildFile::filename = filename;
    CBuildFile::build = false;
+   CBuildFile::have_pkg = false;
    CBuildFile::visited = false;
    CBuildFile::depth = 0;
    CBuildFile::description = "";

src/buildmanager.cc

@@ -93,6 +93,10 @@ void CBuildThread::operator()()
 
       Do("build", buildfile);
 
+      // Test for produced package output
+      if (FileExist(PackagePath(buildfile)))
+         buildfile->have_pkg = true;
+
       // Remove buildfile from active builds
       pthread_mutex_lock(&active_builds_mutex);
       BuildManager.active_builds.remove(buildfile);
@@ -109,8 +113,8 @@ void CBuildThread::operator()()
       BuildOutputPrint();
       pthread_mutex_unlock(&cout_mutex);
 
-      // Don't add last build
-      if (buildfile != last_build)
+      // Don't add last build or builds which have no package output
+      if ((buildfile != last_build) && buildfile->have_pkg)
       {
          pthread_mutex_lock(&add_mutex);
 
@@ -144,7 +148,9 @@ void CBuildThread::operator()()
          Cursor.reset_ymaxpos();
          BuildOutputPrint();
          pthread_mutex_unlock(&cout_mutex);
-      } else
+      }
+
+      if (buildfile == last_build)
       {
          // Clear line if it is the last build
          pthread_mutex_lock(&cout_mutex);

src/include/buildgear/buildfile.h

@@ -59,6 +59,7 @@ class CBuildFile : public CUtility
       string layer;
       char *control_fifo;
       bool build;
+      bool have_pkg;
       bool visited;
       int depth;
       float x;