resolve build failures of node-java in Node v14

This PR updates package.json to get a node-java version
that resolves the subject issue in new branch node14-zos:
https://github.com/ibmruntimes/node-java.git

It also removes the requirement of setting LDFLAGS env var
prior to building node-java or node-jdbc.

Ref: ibmruntimes/node-java#1

Author: gabylb

package.json

@@ -1,11 +1,11 @@
 {
   "name": "jdbc",
-  "version": "0.6.5-pre.0",
+  "version": "0.7.0-pre.0",
   "description": "Node Module JDBC wrapper",
   "main": "index.js",
   "dependencies": {
     "async": "~3.0.1",
-    "java": "git+https://github.com/ibmruntimes/node-java.git#node12-zos",
+    "java": "git+https://github.com/ibmruntimes/node-java.git#node14-zos",
     "lodash": "~4.17.11",
     "uuid": "^3.3.2",
     "winston": "^3.2.1"