This line (introduced in #29071):

        AC_FC_FREEFORM([AC_FC_FUNC([dgeqrf])])

is not executed at all because AC_FC_FREEFORM is AC_DEFUN_ONCE and is called already in gfortran/spkg-configure.m4

As a result:

Checking whether SageMath should install SPKG openblas...
checking BLAS library... openblas
checking whether any of gfortran is installed or will be installed as SPKG... no
checking for openblas >= 0.2.20... yes
checking for cblas_dgemm... yes
checking for ... no
checking for lapack... no
configure: no suitable system package found for SPKG openblas

In this ticket, we fix the check by avoiding AC_FC_FUNC altogether, which is not suitable to be used in a configure that must work if no Fortran compiler is available.

(Factored out from #29104.)

CC: @dimpase

Component: build: configure

Author: Matthias Koeppe

Branch/Commit: 71ac6a5

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/29361