test: avoid memory leak for test_output
test: avoid memory leak for test_output

PR-URL: https://github.com/libuv/libuv/pull/2017
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <838f779c91673db29b8572ea3f54d191d3878ae2@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <b84950071fc99921a72f4fa56f6cad2496b3223c@gmail.com>
Reviewed-By: Santiago Gimeno <3f17e29e343c4cf8809fb0970d81d6d8ee88d6b3@gmail.com>
Reviewed-By: Richard Lau <8193d74c06330af7778ef55510160e4e561ed6a1@uk.ibm.com>
Reviewed-By: John Barboza <f28408917aa66a71bd9f15f4e1bb5c49fa63ce11@ca.ibm.com>

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso