Suspected OOM on PPA builds

Eg, https://launchpadlibrarian.net/266920372/buildlog_ubuntu-xenial-amd64.oxide-qt_1.17.0~git1466545077.d7df86d-0ubuntu0.16.04.1~ppa_BUILDING.txt.gz

[1161/1163] /usr/bin/x86_64-linux-gnu-g++ -Wl,--fatal-warnings -fPIC -Wl,-z,noexecstack -Wl,-z,now -Wl,-z,relro -Wl,-z,defs -fuse-ld=gold -Wl,--icf=safe -pthread -m64 -Wl,-O1 -Wl,--gc-sections -Wl,--as-needed -Wl,-rpath-link=../chromium -Wl,--disable-new-dtags -o "./oxide_qt_unittests" -Wl,--start-group @"./oxide_qt_unittests.rsp" ./libffmpeg.so -Wl,--end-group -ldl -lrt -lnss3 -lnssutil3 -lsmime3 -lplds4 -lplc4 -lnspr4 -lQt5Core -lQt5Feedback -lQt5Gui -lQt5Network -lQt5Positioning -latomic -lfontconfig -lfreetype -lexpat -lgio-2.0 -lgobject-2.0 -lglib-2.0 -lresolv -lX11 -lXcomposite -lXcursor -lXdamage -lXext -lXfixes -lXi -lXrender -lXtst -ldbus-1 -lasound -lm -lgdk_pixbuf-2.0 -lgmodule-2.0 -lgthread-2.0 -lnotify -landroid-properties
[1162/1163] /usr/bin/x86_64-linux-gnu-g++ -Wl,--fatal-warnings -fPIC -Wl,-z,noexecstack -Wl,-z,now -Wl,-z,relro -Wl,-z,defs -fuse-ld=gold -Wl,--icf=safe -pthread -m64 -Wl,-O1 -Wl,--gc-sections -Wl,--as-needed -Wl,-rpath-link=../chromium -Wl,--disable-new-dtags -o "./oxide_shared_unittests" -Wl,--start-group @"./oxide_shared_unittests.rsp" ./libffmpeg.so -Wl,--end-group -ldl -lrt -lnss3 -lnssutil3 -lsmime3 -lplds4 -lplc4 -lnspr4 -lX11 -lXcomposite -lXcursor -lXdamage -lXext -lXfixes -lXi -lXrender -lXtst -lgdk_pixbuf-2.0 -lgobject-2.0 -lglib-2.0 -lgmodule-2.0 -lgthread-2.0 -lnotify -lgio-2.0 -landroid-properties -ldbus-1 -latomic -lfontconfig -lfreetype -lexpat -lresolv -lasound -lm
FAILED: /usr/bin/x86_64-linux-gnu-g++ -Wl,--fatal-warnings -fPIC -Wl,-z,noexecstack -Wl,-z,now -Wl,-z,relro -Wl,-z,defs -fuse-ld=gold -Wl,--icf=safe -pthread -m64 -Wl,-O1 -Wl,--gc-sections -Wl,--as-needed -Wl,-rpath-link=../chromium -Wl,--disable-new-dtags -o "./oxide_qt_unittests" -Wl,--start-group @"./oxide_qt_unittests.rsp" ./libffmpeg.so -Wl,--end-group -ldl -lrt -lnss3 -lnssutil3 -lsmime3 -lplds4 -lplc4 -lnspr4 -lQt5Core -lQt5Feedback -lQt5Gui -lQt5Network -lQt5Positioning -latomic -lfontconfig -lfreetype -lexpat -lgio-2.0 -lgobject-2.0 -lglib-2.0 -lresolv -lX11 -lXcomposite -lXcursor -lXdamage -lXext -lXfixes -lXi -lXrender -lXtst -ldbus-1 -lasound -lm -lgdk_pixbuf-2.0 -lgmodule-2.0 -lgthread-2.0 -lnotify -landroid-properties
collect2: fatal error: ld terminated with signal 9 [Killed]
compilation terminated.