Add top level build script for building packages.

ports/bash/build.sh

Index: ports/bash/build.sh
diff --git a/ports/bash/build.sh b/ports/bash/build.sh
old mode 100755
new mode 100644
index 7036bf2baf005bed57f8e2d24ca3ca853195a8b5..acc8afa346a6f8188994ab5467856a4cd307358b
--- a/ports/bash/build.sh
+++ b/ports/bash/build.sh
@@ -3,8 +3,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source pkg_info
-source ../../build_tools/common.sh
 
 export EXTRA_CONFIGURE_ARGS="--prefix= --exec-prefix="
 export EXTRA_CONFIGURE_ARGS="${EXTRA_CONFIGURE_ARGS} --with-curses"
@@ -51,6 +49,3 @@ InstallStep() {
   ChangeDir ${PUBLISH_DIR}
   LogExecute zip -r bash-7.3.zip bash
 }
-
-PackageInstall
-exit 0