[GLib] Fail to build with rpath-ed Arrow C++ on macOS

http://mail-archives.apache.org/mod_mbox/arrow-dev/201808.mbox/%3C1533195722.2696142.1460869648.3991D444%40webmail.messagingengine.com%3E

I had the same problem with Glib in GISCAN as mentioned in https://github.com/apache/arrow/pull/2303#issuecomment-406934428
I replaced the make call with `LD_LIBRARY_PATH=$ARROW_HOME/lib make` but did not seem to fix
my problem.