IMPALA-3507: Use toolchain linker only if using gold
IMPALA-3507: Use toolchain linker only if using gold

This is a workaround for extremely slow linking when not using gold.

Change-Id: I822a78642993e95abc279944f454fdf67dd8e1d5
Reviewed-on: http://gerrit.cloudera.org:8080/3014
Reviewed-by: Jim Apple <9e3620e7251463d214b5f536438d2c9ea899162d@cloudera.com>
Reviewed-by: Tim Armstrong <2f8e34250f03a653da3dc27f7ec203eafdde80fc@cloudera.com>
Tested-by: Internal Jenkins

cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala