Partially fixes https://github.com/zombiezen/go-sqlite/commit/91ba482a56bdbb52461b23a5f90db2088d39ed19#diff-33ef32bf6c23acb95f5902d7097b7a1d5128ca061167ec0716715b0b9eeaa5f6R17

The other part of the fix is something like

nml@e5-1650:~/src/github.com/zombiezen/go-sqlite$ git diff
diff --git a/sqlite_test.go b/sqlite_test.go
index a008592..a51a160 100644
--- a/sqlite_test.go
+++ b/sqlite_test.go
@@ -900,6 +900,7 @@ func TestSetDefensive(t *testing.T) {
 }

 func TestMain(m *testing.M) {
+       _ = libc.Environ() // Forces libc.SetEnviron, fixes memory accounting ballance for environ(7).
        libc.MemAuditStart()
        rc := m.Run()
        if err := libc.MemAuditReport(); err != nil {
jnml@e5-1650:~/src/github.com/zombiezen/go-sqlite$ go test -tags=libc.memgrind |& tee log
PASS
ok  	zombiezen.com/go/sqlite	6.274s
jnml@e5-1650:~/src/github.com/zombiezen/go-sqlite$