AIDEgen: add -m to enforce rebuilding image.

Bug: 163008223

Test: croot prebuilts/asuite/aidegen
 1. Rebuild docker image:
  ./smoke_tests -m
 2. Print helper message:
  ./smoke_tests -h
 3. Run smoke tests without rebuilding image:
  ./smoke_tests
Change-Id: Iac11608abee7fb0fc746f36a5d10cf583833856d
diff --git a/Dockerfile b/Dockerfile
index d090de4..66e27eb 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -47,11 +47,13 @@
         tzdata \
         python-dev \
         python3-dev \
-        xsltproc
+        xsltproc \
+        sudo
 
 # Configuring tzdata noninteractively
 RUN ln -fs /usr/share/zoneinfo/Asia/Taipei /etc/localtime && \
-    dpkg-reconfigure -f noninteractive tzdata
+    dpkg-reconfigure -f noninteractive tzdata && \
+    echo "${USER} ALL=(ALL:ALL)NOPASSWD: ALL" > /etc/sudoers.d/${USER}
 ENV LANG=C.UTF-8
 
 # Run smoke_tests by default unless overriding the startup command.