Request: support out of tree build #10748

Currently, the configure script and Makefile assume they're being executed with the work tree as the current working directory. This isn't always the case, and supporting out-of-tree building is very useful; it supports automation, and it supports development, in the cases where the make targets change what is/is not installed.

I updated configure to support this, but failed to realize the project is not using Automake, and once I had, didn't attempt to update the Makefile. Certain tools (from the tools/ directory) are hardcoded in the Makefile rules.