FIX don't put data in source dir in bench_covtype

When running under a tool such as @fabianp's profiler yep,
dirname(__file__) is the location of the tool's __main__.py
instead of the benchmarks directory.

Also, we shipped a tarball containing a large dataset before.

Author: larsmans

benchmarks/bench_covertype.py

@@ -55,7 +55,7 @@
 
 import numpy as np
 
-from sklearn.datasets import fetch_covtype
+from sklearn.datasets import fetch_covtype, get_data_home
 from sklearn.svm import LinearSVC
 from sklearn.linear_model import SGDClassifier
 from sklearn.naive_bayes import GaussianNB
@@ -96,9 +96,7 @@
 
 # Memoize the data extraction and memory map the resulting
 # train / test splits in readonly mode
-bench_folder = os.path.dirname(__file__)
-original_archive = os.path.join(bench_folder, 'covtype.data.gz')
-joblib_cache_folder = os.path.join(bench_folder, 'bench_covertype_data')
+joblib_cache_folder = os.path.join(get_data_home(), 'covertype_benchmark_data')
 m = Memory(joblib_cache_folder, mmap_mode='r')