* commit 'acb0dea2':
  build: Split logic for building examples off into a separate Makefile

We already have a Makefile in doc/examples, but it's separate from the build
system and meant to be installed as part of the documentation to help users
compile the installed .c example files.
Move it to Makefile.example to make place for the new build system Makefile.
Merged-by: James Almer <jamrial@gmail.com>