Mac Travis build output truncated, hiding build failure details

This just showed up on PR #4221 3 times in a row (every build there including a restart I tried):

https://travis-ci.com/github/DynamoRIO/dynamorio/jobs/304776211

4080[ 22%] Building C object suite/tests/CMakeFiles/tool.fib_plus.dir/__/__/clients/drcachesim/tests/fib_plus.c.o
4081[ 22%] Linking C executable bin/tool.fib_plus
4082[ 22%] Built target tool.fib_plus
4083[ 22%] 

It looks like something external is killing the build process. Xref #4126 (closed) where the same thing was happening but there it was after 10 minutes: here it's only 1 minute in.