BLD: test_perf will read BUILD_CACHE_DIR from .build_cache_dir if it exists

Author: y-p

.gitignore

@@ -33,3 +33,4 @@ pandas/io/*.json
 .idea/libraries/sass_stdlib.xml
 
 .idea/pandas.iml
+.build_cache_dir

setup.py

@@ -12,7 +12,13 @@
 import warnings
 
 try:
-    BUILD_CACHE_DIR = os.environ.get('BUILD_CACHE_DIR',"")
+    basedir = os.path.dirname(__file__)
+    dotfile = os.path.join(basedir,".build_cache_dir")
+    BUILD_CACHE_DIR = ""
+    if os.path.exists(dotfile):
+        BUILD_CACHE_DIR = open(dotfile).readline().strip()
+    BUILD_CACHE_DIR = os.environ.get('BUILD_CACHE_DIR',BUILD_CACHE_DIR)
+
     if os.path.isdir(BUILD_CACHE_DIR):
         print("--------------------------------------------------------")
         print("BUILD CACHE ACTIVATED. be careful, this is experimental.")