Added jme3-lwjgl3/build/ to the gitignore file.... again..

.gitignore

@@ -146,3 +146,4 @@
 /sdk/nbi/stub/ext/components/products/jdk/build/
 /sdk/nbi/stub/ext/components/products/jdk/dist/
 /sdk/jme3-dark-laf/nbproject/private/
+jme3-lwjgl3/build/