build-buildroot: fix is LD_LIBRARY_PATH is not defined

confiure: install rsync for docker

common.py

@@ -277,7 +277,8 @@ def run_cmd(
     env = os.environ.copy()
     env.update(extra_env)
     for key in delete_env:
-        del env[key]
+        if key in env:
+            del env[key]
     if show_cmd:
         print_cmd(cmd, cmd_file, extra_env=extra_env)
     # Otherwise Ctrl + C gives:

configure

@@ -44,6 +44,7 @@ cpio \
 expect \
 git \
 moreutils \
+rsync \
 tmux \
 unzip \
 vinagre \