Fix potential index out of range error

I had some extra spaces and junk in my ssh config and it was causing
this part of the code to fail with an out of range error.

config_test.go

@@ -324,3 +324,17 @@ func TestMatchUnsupported(t *testing.T) {
 		t.Errorf("wrong error: %v", err)
 	}
 }
+
+func TestIndexInRange(t *testing.T) {
+	us := &UserSettings{
+		userConfigFinder: testConfigFinder("testdata/config4"),
+	}
+
+	user, err := us.GetStrict("wap", "User")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if user != "root" {
+		t.Errorf("expected User to be %q, got %q", "root", user)
+	}
+}

parser.go

@@ -107,19 +107,17 @@ func (p *sshParser) parseKV() sshParserStateFn {
 	}
 	if strings.ToLower(key.val) == "host" {
 		strPatterns := strings.Split(val.val, " ")
+		patterns := make([]*Pattern, 0)
 		for i := range strPatterns {
 			if strPatterns[i] == "" {
-				strPatterns = append(strPatterns[:i], strPatterns[i+1:]...)
+				continue
 			}
-		}
-		patterns := make([]*Pattern, len(strPatterns))
-		for i := range strPatterns {
 			pat, err := NewPattern(strPatterns[i])
 			if err != nil {
 				p.raiseErrorf(val, "Invalid host pattern: %v", err)
 				return nil
 			}
-			patterns[i] = pat
+			patterns = append(patterns, pat)
 		}
 		p.config.Hosts = append(p.config.Hosts, &Host{
 			Patterns:   patterns,

testdata/config4

@@ -0,0 +1,4 @@
+# Extra space at end of line is important.
+Host wap     
+  User root
+  KexAlgorithms diffie-hellman-group1-sha1