buildman: Add support for building a buildman PyPi package

Create the necessary files to build this new package.

It is not actually clear whether this is useful, since buildman has no
purpose outside U-Boot. It is included for completeness, since adding
this later would be more trouble.

Move the main program into a function so that it can easily be called by
the PyPi-created script.

Signed-off-by: Simon Glass <sjg@chromium.org>

Makefile

@@ -2283,6 +2283,7 @@ pip pip_test pip_release: _pip
 _pip:
 	scripts/make_pip.sh u_boot_pylib ${PIP_ARGS}
 	scripts/make_pip.sh patman ${PIP_ARGS}
+	scripts/make_pip.sh buildman ${PIP_ARGS}
 
 help:
 	@echo  'Cleaning targets:'

tools/buildman/pyproject.toml

@@ -0,0 +1,29 @@
+[build-system]
+requires = ["setuptools>=61.0"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "buildman"
+version = "0.0.2"
+authors = [
+  { name="Simon Glass", email="sjg@chromium.org" },
+]
+dependencies = ["u_boot_pylib", "patch-manager"]
+description = "Buildman build tool for U-Boot"
+readme = "README.rst"
+requires-python = ">=3.7"
+classifiers = [
+    "Programming Language :: Python :: 3",
+    "License :: OSI Approved :: GNU General Public License v2 or later (GPLv2+)",
+    "Operating System :: OS Independent",
+]
+
+[project.urls]
+"Homepage" = "https://u-boot.readthedocs.io/en/latest/build/buildman.html"
+"Bug Tracker" = "https://source.denx.de/groups/u-boot/-/issues"
+
+[project.scripts]
+buildman = "buildman.main:run_buildman"
+
+[tool.setuptools.package-data]
+buildman = ["*.rst"]