Adapt abicheck.cc to deal with newer GCC version

We need to adapt our abicheck.cc to work as it is supposed to with GCC 9.

Trac:
Parent Ticket: legacy/trac#34228 (moved)

added component::applications/tor browser in Legacy / Trac ff78-esr in Legacy / Trac gitlab-tb-tor-browser-build in Legacy / Trac owner::tbb-team in Legacy / Trac parent::34228 in Legacy / Trac priority::medium in Legacy / Trac severity::normal in Legacy / Trac status::new in Legacy / Trac tbb-rbm in Legacy / Trac type::task in Legacy / Trac labels

Trac:
Type: defect to task

Add magic gitlab keyword.

Trac:
Keywords: N/A deleted, gitlab-tb-tor-browser-build added

mentioned in issue legacy/trac#34228 (moved)

moved from legacy/trac#34359 (moved)

mentioned in issue #34228 (closed)

added Task label and removed 1 deleted label

removed 1 deleted label

added 1 deleted label

added Doing label

assigned to @gk

changed time estimate to 1h

mentioned in issue #40030 (closed)

mentioned in merge request !28 (closed)

added 2h of time spent at 2020-08-12

added 1h of time spent at 2020-08-13

mentioned in merge request !30 (closed)

Merged with commit 756b3f0a6f3dd6b0a6ce262528f027f79b1e3c07 on master (based on !30 (closed))

closed

mentioned in merge request tor-browser-bundle-testsuite!1 (closed)