* Update infra/base-images/all.sh

Add build of base-sanitizer-libs-builder and msan-libs-builder to this
shell script.

* msan: Don't warn on un-instrumented standard libs

These libraries do not need to be built with instrumentation, because
MemorySanitizer includes interceptors for them.

* Fix indentation

* Add missing docstrings

* Fix unused variable

* Fix invalid names

* Install python-apt on CI

* Revert "Install python-apt on CI"

This reverts commit d3da49c.

* Install and use python-apt in system directory

* Revert "Install and use python-apt in system directory"

This reverts commit e0ede10.

* Build python-apt from source

* Check out correct version of python-apt

* Fix octal literals

* More indentation fixes

* Add more missing docstrings

* Change variable names of opened files

* Remove unused import

* Ignore lints about package.Package API

* Fix or ignore remaining invalid names

* Fix apparent typo in compiler_wrapper_test.py

-z should precede a keyword, not a long option

* Fix use of xrange

* Style fixes, compiler_wrapper

* Fix apparent error in compiler_wrapper_test.py

Similar to the previous error, the test case would pass "-z
--no-undefined" to the linker. "-z" only has an effect when it is
followed by a keyword, otherwise ld ignores it and prints a warning
message. In this test case, "-z" and "--no-undefined" were passed in two
separate "-Wl," compiler arguments, but they reflect a common issue.

* Add missing license header

* Rename more functions

* Better name for global variable

* Rename methods of Package

* Rename functions in msan_builder.py

* Fix invalid variable names

* Fix useless-object-inheritance

* pylint: Fixes for Package and its subclasses

* Remove unused imports

* Indentation fixes

* Fix too-may-locals error in msan_build.py

* Add missing docstrings