Comment by dredmorbius

Free Software Foundation General Public License version 2:

The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable.

<https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>

That's generally interpreted to mean that the build environment or build system is included in the requirements of the licence. This is included in FSF's Free Software Definition as well:

<https://www.gnu.org/philosophy/free-sw.html>

OSI's Open Source Definition includes substantively similar language:

The source code must be the preferred form in which a programmer would modify the program.

<https://opensource.org/osd>

Answering your question then, no, source absent build prerequisites / systems does not satisfy either FSF's Free Software Definition or the subsequent Open Source Definition by the Open Source Initiative.