openblas: clear out .pc symlinks before installation

[mkoeppe]

When switching from system BLAS to SPKG openblas, the following errors have been reported:

Copying package files from temporary location /Users/yzh/sagecopies/sage/worktree-2020/local/var/tmp/sage/build/openblas-0.3.9/inst to /Users/yzh/sagecopies/sage/worktree-2020/local
cp: /Users/yzh/sagecopies/sage/worktree-2020/local/./lib/pkgconfig/cblas.pc: Permission denied
cp: /Users/yzh/sagecopies/sage/worktree-2020/local/./lib/pkgconfig/blas.pc: Permission denied
cp: /Users/yzh/sagecopies/sage/worktree-2020/local/./lib/pkgconfig/lapack.pc: Permission denied
************************************************************************
Error copying files for openblas-0.3.9.

The correct fix is described in #29585 comment:9
and #29387 + #29386

This ticket is a quick workaround for Sage 9.2.

CC: @yuan-zhou @jhpalmieri @dimpase @embray

Component: build

Author: Matthias Koeppe

Branch: 29b1ff8

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/30335

[mkoeppe]

Branch: u/mkoeppe/openblas__clear_out__pc_symlinks_before_installation

[mkoeppe]

New commits:

29b1ff8

build/pkgs/openblas/spkg-install.in: Clear out possible .pc symlinks before installation

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Commit: 29b1ff8

[dimpase]

Reviewer: Dima Pasechnik

[dimpase]

comment:3

lgtm

[mkoeppe]

comment:4

Thanks!

[vbraun]

Changed branch from u/mkoeppe/openblas__clear_out__pc_symlinks_before_installation to 29b1ff8

[embray]

comment:6

Ah, no, spkg-install scripts should not make changes to $SAGE_LOCAL. If it's absolutely necessary to you can do that in an spkg-preinst script.

[embray]

Changed commit from 29b1ff8 to none

[mkoeppe]

comment:7

Follow-up: #30480