Fix generation of license header for java

Summary:
If you run ```enums.py``` it will revert the changes from 835b2bb . This changes the license header for java to  not be a javadocs comment.
Closes https://github.com/facebook/yoga/pull/660

Differential Revision: D6407985

Pulled By: emilsjolander

fbshipit-source-id: 49efe555fecb8d740675c6b4631dce2a64f10417

enums.py

@@ -181,7 +181,7 @@ with open(root + '/yoga/YGEnums.cpp', 'w') as f:
 # write out java files
 for name, values in sorted(ENUMS.items()):
     with open(root + '/java/com/facebook/yoga/Yoga%s.java' % name, 'w') as f:
-        f.write(LICENSE)
+        f.write(LICENSE.replace('/**', '/*', 1))
         f.write('package com.facebook.yoga;\n\n')
         f.write('import com.facebook.proguard.annotations.DoNotStrip;\n\n')
         f.write('@DoNotStrip\n')