correct AC_CHECK_PROG call in spkg-configure for bzip2

[dimpase]

as noticed in #27182 comment:12
it is incorrect, and always fails

configure:10531: checking for break
configure:10561: result: no

As the fail action is noop, it "works", always.

CC: @orlitzky

Component: build: configure

Author: Dima Pasechnik

Branch/Commit: 03ded4b

Reviewer: Erik Bray, Michael Orlitzky

Issue created by migration from https://trac.sagemath.org/ticket/28956

[dimpase]

Branch: u/dimpase/packages/bz2fix

[dimpase]

Author: Dima Pasechnik

[sagetrac-git]

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

6b64d68

correct AC_CHECK/PATH_PROG call, refactor

[sagetrac-git]

Commit: 6b64d68

[embray]

Reviewer: Erik Bray

[orlitzky]

Changed reviewer from Erik Bray to Erik Bray, Michael Orlitzky

[orlitzky]

comment:5

I still think this is funky. If I rename my /bin/bzip2 program, the test succeeds:

$ sudo mv /bin/bzip2 /bin/bzip2.bak
$ ./configure
...
configure: === checking whether to install the bzip2 SPKG ===
checking bzlib.h usability... yes
checking bzlib.h presence... yes
checking for bzlib.h... yes
checking for library containing BZ2_bzCompress... -lbz2
checking for bzip2... sage_spkg_install_bzip2=yes
...
    bzip2-1.0.6-20150304.p0 will not be installed (configure check)

The value of the bzip2prog variable is being set to the string sage_spkg_install_bzip2=yes but that snippet is never actually executed.