Add some sig_on() in Singular library

[jdemeyer]

This hangs (see #15710) and cannot be interrupted:

sage: F.<a>=CyclotomicField(49); G = F['z,w'].fraction_field(); 1/G(a^28 + a^23 - 1)

The attached branch fixes the "cannot be interrupted" part of the bug.

Depends on #14333

CC: @ppurka

Component: interfaces

Author: Jeroen Demeyer

Branch/Commit: u/jdemeyer/ticket/15717 @ 13573a9

Reviewer: Punarbasu Purkayastha

Issue created by migration from https://trac.sagemath.org/ticket/15717

[jdemeyer]

Branch: u/jdemeyer/ticket/15717

[jdemeyer]

Commit: 13573a9

[jdemeyer]

New commits:

1753f06	Update Singular to version 3-1-6.
536a31f	Update Singular function interface to API changes in Singular 3.1.6.
dd46991	Remove description of deleted patches.
0a702e9	Merge commit 'dd469911d19ed7080fec' into ticket/15710
13573a9	Add some sig_on() blocks to Singular interface

[jdemeyer]

Dependencies: #14333

[ppurka]

comment:4

Thanks, I just tested it and this works. But, we don't need #14333. I just cherry-picked the last commit on to develop and the interrupt worked very well. :)

[jdemeyer]

comment:5

Sure, but I started #15710 by checking whether #14333 would fix it and any fix for #15710 would probably need to be based on #14333. And I just copied that commit here. Given that #14333 has positive review, it's not a problem, right?

[ppurka]

Reviewer: Punarbasu Purkayastha

[ppurka]

comment:6

Yeah. I guess it shouldn't matter.