Don't use gold for the Gitian builds

Summary:
For some reason, gold will produce a bad executable on linux when
building against the static depends. The build runs fine, is
deterministic, but running bitcoind or bitcoin-qt make them stuck -
they won't return, no error, won't shutdown and need to be killed.
The last debug.log line is:

Using at most 125 automatic connections (1024 file descriptors available)

This needs to be investigated, but for now the gold linker is disabled.

Test Plan: Run the linux Gitian build then launch the bitcoind executable.

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D5479