Changes

''As an aside, and while you are thinking about Makefiles, you might take a moment to read [https://bugzilla.mozilla.org/show_bug.cgi?id=371201 bug 371201]. This is a bug that was identified while the author was trying to make debug his Makefile.in files. Ted Mielczarek (luser on IRC) was finally able to spot the problem--a trailing space on XPI_NAME. I share this anecdote as a way to introduce https://bugzilla.mozilla.org, to emphasize the necessity of the community, and to show the kind of problems that one can have writing files for the build system.''