Add NTL to cython_aliases and sage.misc.cython library search dirs

[mkoeppe]

(from #31348)

... using SAGE_NTL_PREFIX via sage_conf.

This is for macOS with configurations in which Python extensions no longer have access to /usr/local due to the use of -isysroot in the compiler configuration from sysconfig.

In particular, we add handling for ntl to the .homebrew-build-env script -- so that after brew install ntl; brew unlink ntl, our ./configure still finds NTL.

Depends on #30770
Depends on #31344

CC: @zlscherr @dimpase @orlitzky @videlec @kliem @jhpalmieri @kiwifb

Component: build: configure

Author: Matthias Koeppe

Branch/Commit: dbcbf79

Reviewer: Jonathan Kliem

Issue created by migration from https://trac.sagemath.org/ticket/31365

[mkoeppe]

Dependencies: #30770

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Changed dependencies from #30770 to #30770, #31344

[mkoeppe]

Branch: u/mkoeppe/add_ntl_to_cython_aliases

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

32576b4

sage.misc.cython: Add NTL aliases, cache result of cython_aliases

[sagetrac-git]

Commit: 32576b4

[mkoeppe]

comment:6

Actually spkg-configure.m4 needs some work too - need to use AX_ABSOLUTE_HEADER to set SAGE_NTL_PREFIX

[sagetrac-git]

Changed commit from 32576b4 to 7b1e27b

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

6e30e3a	Use variables NTL_INCDIR, NTL_LIBDIR in sage_conf, separate from NTL_PREFIX used in sage-build-env-config; set -std=c++11 in NTL_CFLAGS
7b1e27b	Merge distutils directives for Cython files using ntl

[mkoeppe]

Description changed:

--- 
+++ 
@@ -2,4 +2,6 @@
 
 ... using `SAGE_NTL_PREFIX` via `sage_conf`.
 
+This is for macOS with configurations in which Python extensions no longer have access to `/usr/local` due to the use of `-isysroot` in the compiler configuration from sysconfig.
 
+

[mkoeppe]

comment:9

NTL_INCDIR, NTL_LIBDIR needs more work.

NTL_INCDIR = ".
.
///usr/include/NTL"

[sagetrac-git]

Changed commit from 7b1e27b to 993c35c

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

4d2828d	Switch Cython files that use NTL to language = c++
993c35c	build/pkgs/ntl/spkg-configure.m4: Fix up

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

dbcbf79

.homebrew-build-env: Add ntl dirs

[sagetrac-git]

Changed commit from 993c35c to dbcbf79