Some changes added to compile and run with Java 6 and Java 7.

  + [base/**/jni_generator.py]
      javap 5 and 6 don't show generics.
      This feature is added on javap 7 and higher.
      To retrieve the same behavior, javap (7 and higher) have a new option "-XDcompat".

Change-Id: I761064f14dcb38d52fd735ef462a2c08b8c12cab
Signed-off-by: Jerome Pilliet <pilliet@univ-mlv.fr>
Fix JNI generation on Darwin and XCode 5.1

clang now errors out if an unknown argument is used:
$ cpp -fpreprocessed
clang: error: unknown argument: '-fpreprocessed' [-Wunused-command-line-argument-hard-error-in-future]
clang: note: this will be a hard error (cannot be downgraded to a warning) in the future

This is ugly but works...

Change-Id: I47d91f132f6222413147807ffd2ac5bcc4256896