spkg-configure.m4 for pkgconf

[dimpase]

pkgconf is an implementation of widely used pkg-config.
In fact, pkg-config can be configured to look at certain directories, so we can use the one on the system.

This is what the branch does - it check for pkg-config presense,
and if it is there is sets up/updates the env.var. PKG_CONFIG_PATH
in src/bin/sage-env-config. As pkg-config looks in dirs in PKG_CONFIG_PATH first, anything that Sage installs there overrides the system ones.

CC: @embray @kiwifb @isuruf @antonio-rojas

Component: build: configure

Author: Dima Pasechnik

Branch/Commit: ed84fa2

Reviewer: Isuru Fernando

Issue created by migration from https://trac.sagemath.org/ticket/27827

[embray]

comment:1

As the Sage-8.8 release milestone is pending, we should delete the sage-8.8 milestone for tickets that are not actively being worked on or that still require significant work to move forward. If you feel that this ticket should be included in the next Sage release at the soonest please set its milestone to the next release milestone (sage-8.9).

[dimpase]

comment:2

the plan is to install PKG_CONFIG_PATH=SAGE_LOCAL/lib/pkgconfig into src/bin/sage-env-config in case the system has pkg-config installed.

[dimpase]

New commits:

f77b4c1

spkg-configure.m4 for pkgconf

[dimpase]

Author: Dima Pasechnik

[dimpase]

Branch: u/dimpase/packages/pkgconf

[dimpase]

Commit: f77b4c1

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

836f5ba

spkg-configure.m4 for pkgconf

[sagetrac-git]

Changed commit from f77b4c1 to 836f5ba

[isuruf]

comment:7

Works for me

[isuruf]

Reviewer: Isuru Fernando

[sagetrac-git]

Changed commit from 836f5ba to 3b95f60

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1 and set ticket back to needs_review. This was a forced push. New commits:

3b95f60

spkg-configure.m4 for pkgconf

[dimpase]

comment:9

rebased over 8.9.beta3

[vbraun]

comment:10

Merge conflict

[sagetrac-git]

Changed commit from 3b95f60 to ed84fa2

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

ed84fa2

spkg-configure.m4 for pkgconf

[dimpase]

comment:12

rebased over Sage 8.9.beta4

[vbraun]

Changed branch from u/dimpase/packages/pkgconf to ed84fa2