Add Theano flag cmodule.age_thresh_use

doc/library/config.txt

@@ -1071,6 +1071,14 @@ import theano and print the config variable, as in:
 
     If set to True, will preload the C module cache at import time
 
+.. attribute:: config.cmodule.age_thresh_use
+
+    Int value, default: ``60 * 60 * 24 * 24``  # 24 days
+
+    In seconds. The time after which a compiled c module won't be
+    reused by Theano. Automatic deletion of those c module 7 days
+    after that time.
+
 .. attribute:: config.traceback.limit
 
     Int value, default: 8

theano/configdefaults.py

@@ -1143,6 +1143,13 @@ AddConfigVar('cmodule.preload_cache',
              BoolParam(False, allow_override=False),
              in_c_key=False)
 
+AddConfigVar('cmodule.age_thresh_use',
+             "In seconds. The time after which "
+             "Theano won't reuse a compile c module.",
+             # 24 days
+             IntParam(60 * 60 * 24 * 24, allow_override=False),
+             in_c_key=False)
+
 
 def default_blas_ldflags():
     global numpy

theano/gof/cmodule.py

@@ -669,7 +669,7 @@ class ModuleCache(object):
         if do_refresh:
             self.refresh()
 
-    age_thresh_use = 60 * 60 * 24 * 24    # 24 days
+    age_thresh_use = config.cmodule.age_thresh_use  # default 24 days
     """
     The default age threshold (in seconds) for cache files we want to use.
 
@@ -1241,7 +1241,8 @@ class ModuleCache(object):
 
         self.time_spent_in_check_key += time.time() - start_time
 
-    age_thresh_del = 60 * 60 * 24 * 31  # 31 days
+    # default 31 days
+    age_thresh_del = config.cmodule.age_thresh_use + 60 * 60 * 24 * 7
     age_thresh_del_unversioned = 60 * 60 * 24 * 7  # 7 days
     """
     The default age threshold for `clear_old` (in seconds).