RT3497: The ticket that keeps on giving.

Don't remove c_rehash that wasn't created by make; this script
is created by configure.

This fix brought to you by the letter "f" and
Reviewed-by: NEmilia Kasper <emilia@openssl.org>

tools/Makefile

@@ -52,7 +52,6 @@ dclean:
 
 clean:
 	rm -f *.o *.obj lib tags core .pure .nfs* *.old *.bak fluff
-	rm -f c_rehash
 
 errors: