README Build from Source: m4 (step 5) is needed to run make configure (step 3)

[seblabbe]

In the current README (https://gitlab.com/sagemath/sage/-/blob/develop/README.md), in the Instructions to Build from Source section, it says at step 3 to:

3. [Git] If you cloned the Sage repository using git, bootstrap the
source tree using:

$ make configure

On a bare debian linux version, the above fails becaue of the absence of m4.

The installation of m4 is suggested only at step 5:

5. [Linux, Cygwin] Install the required minimal build prerequisites.


Compilers: gcc, gfortran, g++ (a recent enough matching
set of these three will avoid building Sage-specific compilers).
See the Installation Manual for a discussion of suitable compilers.


Build tools: GNU make, GNU m4, perl (including
ExtUtils::MakeMaker), ranlib, git, tar, bc.


Python 3.4 or later, or Python 2.7, a full installation including
urllib; but ideally version 3.7.x, 3.8.x, or 3.9.x, which will
avoid having to build Sage's own copy of Python 3.

Component: documentation

Author: Matthias Koeppe

Branch/Commit: f1af3cb

Reviewer: Sébastien Labbé

Issue created by migration from https://trac.sagemath.org/ticket/33553

[mkoeppe]

Branch: u/mkoeppe/readme_build_from_source__m4__step_5__is_needed_to_run__make_configure___step_3_

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

New commits:

1872edc	README.md: Move installation step on minimal build prereqs earlier
eb94fcf	README.md: Also mention bootstrapping prerequisites

[mkoeppe]

Commit: eb94fcf

[seblabbe]

Changed commit from eb94fcf to f1af3cb

[seblabbe]

comment:3

The change 9. to 10. needed to remove one space. I added a commit to fix this in case this changes the layout (I have more experience with !ReST than with markdown, so I don't know).

---

New commits:

f1af3cb

33553: removed one space after `10.`

[seblabbe]

Changed branch from u/mkoeppe/readme_build_from_source__m4__step_5__is_needed_to_run__make_configure___step_3_ to public/33553

[seblabbe]

Reviewer: Sébastien Labbé

[seblabbe]

comment:4

For me it is a positive review. Feel free to change to positive review if you agree with my commit.

[mkoeppe]

comment:5

Thank you!

[vbraun]

Changed branch from public/33553 to f1af3cb