Fix OSX compile errors/warnings

I just tried installing from source on OSX 10.9.4 and it failed with various errors and warnings. This should fix it. Though there was still a warning about tOffset (long long *) not matching jlong (long *):

    src/hadoop-2.4.0.patched/libhdfs/hdfs.c:2331:49: warning: incompatible pointer types passing 'tOffset *' (aka 'long long *') to parameter of type 'jlong *' (aka 'long *')
          [-Wincompatible-pointer-types]
        jthr = getDefaultBlockSize(env, jFS, jPath, &blockSize);
                                                    ^~~~~~~~~~
    src/hadoop-2.4.0.patched/libhdfs/hdfs.c:787:61: note: passing argument to parameter 'out' here
                                          jobject jPath, jlong *out)
                                                                ^
    1 warning generated.

Unfortunately I couldn't figure out how that patched code was generated in order to fix it. In all the hdfs.c files in the source repo, it looked like the pointer types agreed with each other.