[PULL 16/17] tests/qtest/migration-test: Use g_autofree to avoid leaks on error paths

From: Peter Maydell Coverity notices that several places in the migration-test code fail to free memory in error-exit paths. This is pretty unimportant in test case code, but we can avoid having to manually free the memory entirely by using g_autofree. The places where Coverity spotted a leak

[PULL 16/17] tests/qtest/migration-test: Use g_autofree to avoid leaks on error paths

From: Peter Maydell Coverity notices that several places in the migration-test code fail to free memory in error-exit paths. This is pretty unimportant in test case code, but we can avoid having to manually free the memory entirely by using g_autofree. The places where Coverity spotted a leak