add runtime checks for undefined behavior

[dlangBugzillaToGithub]

Walter Bright (@WalterBright) reported this on 2014-10-18T23:51:26Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=13636

Description

Some undefined behaviors can only be detected at runtime, such as array bounds checking. An undefined behavior checker for C is ubsan:

http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/

Those relevant to D and not already in D can be added with a compile time switch.