use __FILE__, not __BASE_FILE__

The intention was to use the file's basename, but __BASE_FILE__ means "the root
file that is being parsed and contains #include statements".

If we had a function using __BASE_FILE__ and that was defined in an #included
file, __BASE_FILE__ would indicate the first file where the #include is, and
not the file where the function is defined. __BASE_FILE__ works for us because
we don't ever include function definitions that log something, so __BASE_FILE__
always coincides with __FILE__ for our logging; but still __BASE_FILE__ is
semantically the wrong constant.

Related: OS#2740
Change-Id: Icdf7af7a31fbba9197b3711eaf102fc0ae333bcc
diff --git a/include/osmocom/sgsn/gprs_subscriber.h b/include/osmocom/sgsn/gprs_subscriber.h
index be78feb..d36db75 100644
--- a/include/osmocom/sgsn/gprs_subscriber.h
+++ b/include/osmocom/sgsn/gprs_subscriber.h
@@ -27,5 +27,5 @@
 				     const char *file, int line);
 struct gprs_subscr *_gprs_subscr_put(struct gprs_subscr *gsub,
 				     const char *file, int line);
-#define gprs_subscr_get(gsub) _gprs_subscr_get(gsub, __BASE_FILE__, __LINE__)
-#define gprs_subscr_put(gsub) _gprs_subscr_put(gsub, __BASE_FILE__, __LINE__)
+#define gprs_subscr_get(gsub) _gprs_subscr_get(gsub, __FILE__, __LINE__)
+#define gprs_subscr_put(gsub) _gprs_subscr_put(gsub, __FILE__, __LINE__)