Linkage against librrd_th

[valobanov]

Hello,

By default, my project links against not thread safe libbrrd that causes mess with errors from different Update() calls.
Changing #cgo pkg-config: librrd directive to #cgo LDFLAGS: -lrrd_th in rrd_c.go fixes the issue.
What is the suggested way to link against thread safe library when using pkg-config?

This commit switched setting of linker options to pkg-config for the reason not clear from the comment.

Thanks,
Vadim

[vbatoufflet]

Hi @valobanov,

The change was detailed in the associated PR: #15.

Regards.