Don't set -extldflags unless LDFLAGS has a value

[hartzell]

Unconditionally setting -extldflags to the contents of LDFLAGS
causes problems when LDFLAGS isn't defined (-extldflags doens't
have an corresponding value).

In out case this led to git-lfs aborting.

$ ./bin/git-lfs
Aborted

This change only sets -extldflags if LDFLAGS is defined.

[bk2204]

Hey, thanks for the patch and welcome to Git LFS!

I think this looks obviously correct. I'm not sure why we abort in this case; it's likely due to something in Go itself on whatever version you're building on. I will admit I'm curious as to why this fails for you and what version of Go you're building against, but that shouldn't prevent us from merging this as it stands.

It looks like from the repo you've linked, that you might be building against Go 1.5. Is that correct? If so, it might be worth using a newer version, since we generally only support the latest version of Go and don't test against older versions.

[hartzell]

We use the Spack package manager to build a variety of things. We recently noticed that we had builds of git-lfs that didn't work. Sometimes. Dig, dig, dig and I ended up with this.

We're building on minimal-ish CentOS 7 systems (not very many packages installed).

I'm running a fairly recent version of go, I'm not sure what you see that makes you think [email protected]:

$ which go
~/spack/opt/spack/linux-centos7-x86_64/gcc-8.2.0/go-1.11.5-pei4g2iupo6y2yvogg4vde2poix2ho7d/bin/go
$ go version
go version go1.11.5 linux/amd64
[ghartzell@bifx1n03 git-lfs]$

I'm tracking this discussion over here: spack/spack#10702

[bk2204]

I'm running a fairly recent version of go, I'm not sure what you see that makes you think [email protected]:

Ah, I saw the build-dependency listed in this file and thought it might have been an old version of Go.

I'm going to merge this, and if we do a 2.7.2 release, I'll make sure we include it.

[hartzell]

[edit: "At" -> "Ah"]

Ah, that build dependency is [email protected] or later. The spack "concretizer" (SAT solver) will put together a graph that satisfies the various requirements/constraints, generally preferring the newest version that it knows about.