Update infrastructure to the fact that the bench directory has been deleted

Makefile

@@ -66,7 +66,6 @@ doc:	html doc/depend.png
 clean:
 	cd tests && $(MAKE) clean
 	cd example && $(MAKE) clean
-	cd bench && $(MAKE) clean
 	$(RM) README.html depend.dot
 	$(RM) -r 'm_lib-$(VERSION)'
 	$(RM) 'm_lib-$(VERSION).tar.bz2'

README.md

@@ -511,7 +511,7 @@ M\*LIB performance is compared to the one of GNU C++ STL (v10.2) in the followin
 Each graph is presented first in linear scale and then in logarithmic scale to better realize the differences.
 M\*LIB is on par with the STL or even faster.
 
-All used bench codes are available in the bench directory.
+All used bench codes are available in this [repository](https://github.com/P-p-H-d/c-stl-comparison)
 The results for several different libraries are also available [in a separate page](https://github.com/P-p-H-d/mlib/wiki/performance).
 
 #### Singly List