Enable makezero linter and fix issue (#881)

Reference: #865

Previously:

```text
terraform/state_filter.go:39:8: append to slice `as` with non-zero initialized length (makezero)
                as = append(as, &resourceAddress{Index: -1})
                     ^
```

Author: bflad

.golangci.yml

@@ -16,7 +16,7 @@ linters:
     - gofmt
     - gosimple
     # - ineffassign # TODO: https://github.com/hashicorp/terraform-plugin-sdk/issues/865
-    # - makezero # TODO: https://github.com/hashicorp/terraform-plugin-sdk/issues/865
+    - makezero
     - nilerr
     # - paralleltest # Reference: https://github.com/kunwardeep/paralleltest/issues/14
     - predeclared

terraform/state_filter.go

@@ -24,7 +24,15 @@ type stateFilter struct {
 // parseResourceAddress.
 func (f *stateFilter) filter(fs ...string) ([]*stateFilterResult, error) {
 	// Parse all the addresses
-	as := make([]*resourceAddress, len(fs))
+	var as []*resourceAddress
+
+	if len(fs) == 0 {
+		// If we weren't given any filters, then we list all
+		as = []*resourceAddress{{Index: -1}}
+	} else {
+		as = make([]*resourceAddress, len(fs))
+	}
+
 	for i, v := range fs {
 		a, err := parseResourceAddress(v)
 		if err != nil {
@@ -34,11 +42,6 @@ func (f *stateFilter) filter(fs ...string) ([]*stateFilterResult, error) {
 		as[i] = a
 	}
 
-	// If we weren't given any filters, then we list all
-	if len(fs) == 0 {
-		as = append(as, &resourceAddress{Index: -1})
-	}
-
 	// Filter each of the address. We keep track of this in a map to
 	// strip duplicates.
 	resultSet := make(map[string]*stateFilterResult)