[coin-or-*] Disable finding mkl, always use lapack.pc

[BillyONeal]

This removes explicit detection in coin-or-buildtools that started picking up intel-mkl.lib after #47633

Related #47764

[BillyONeal]

@Neumann-A Do you think this is reasonable or ... ?

[Neumann-A]

I dont mind if it is generally looking for lapack/blas some other way (e.g. pkgconfig)

[BillyONeal]

I dont mind if it is generally looking for lapack/blas some other way (e.g. pkgconfig)

After the removed chunk it has:

dnl If none of the above worked, check whether lapack.pc blas.pc exists and
dnl links. We check for both to ensure that blas lib also appears on link line
dnl in case someone wants to use Blas functions but tests only for Lapack.
dnl We skip this if int64
  if test "$lapack_keep_looking" = yes ; then
    AC_COIN_CHK_MOD_EXISTS([lapack],[lapack blas],
           [lapack_what="generic module (lapack.pc blas.pc)"
            AC_COIN_TRY_LINK([dsyev],[],[lapack],
              [coin_has_lapack=yes
               lapack_keep_looking=no
               lapack_pcfiles="lapack blas"],
              [AC_MSG_WARN([lapack.pc and blas.pc present, but could not find dsyev when trying to link with LAPACK.])],no)
           ])
  fi