use localtime/localtimestamp on HSQL and Postgres

Since we don't need the TIME ZONE for our current_time
and current_timestamp functions, these are cleaner
mappings to SQL for these functions.

hibernate-core/src/main/java/org/hibernate/dialect/HSQLDialect.java

@@ -212,6 +212,21 @@ public void initializeFunctionRegistry(QueryEngine queryEngine) {
 		}
 	}
 
+	@Override
+	public String currentTime() {
+		return "localtime";
+	}
+
+	@Override
+	public String currentTimestamp() {
+		return "localtimestamp";
+	}
+
+	@Override
+	public String currentTimestampWithTimeZone() {
+		return "current_timestamp";
+	}
+
 	@Override
 	public SqlAstTranslatorFactory getSqlAstTranslatorFactory() {
 		return new StandardSqlAstTranslatorFactory() {

hibernate-core/src/main/java/org/hibernate/dialect/PostgreSQLDialect.java

@@ -122,6 +122,21 @@ public int getVersion() {
 		return version;
 	}
 
+	@Override
+	public String currentTime() {
+		return "localtime";
+	}
+
+	@Override
+	public String currentTimestamp() {
+		return "localtimestamp";
+	}
+
+	@Override
+	public String currentTimestampWithTimeZone() {
+		return "current_timestamp";
+	}
+
 	/**
 	 * The {@code extract()} function returns {@link TemporalUnit#DAY_OF_WEEK}
 	 * numbered from 0 to 6. This isn't consistent with what most other