Incorporate table into H2 column constraint name

This permits using the same boolean column name across multiple tables.

Change-Id: Ia9e14069d9eed2209ec975959fe3bdca0dc02003

src/main/java/com/google/gwtorm/schema/sql/DialectH2.java

diff --git a/src/main/java/com/google/gwtorm/schema/sql/DialectH2.java b/src/main/java/com/google/gwtorm/schema/sql/DialectH2.java
index 5111b72..c676715 100644
--- a/src/main/java/com/google/gwtorm/schema/sql/DialectH2.java
+++ b/src/main/java/com/google/gwtorm/schema/sql/DialectH2.java
@@ -91,7 +91,7 @@
       r.append("ALTER TABLE ");
       r.append(tableName);
       r.append(" ADD CONSTRAINT ");
-      r.append(col.getColumnName() + "_check");
+      r.append(tableName + "_" + col.getColumnName() + "_check");
       r.append(' ');
       r.append(check);
       stmt.execute(r.toString());