The ECM modules aren't installed nor redistributed with the binaries,
they're just used while developing. Also don't want to create licensing
confusion
ECMEnableSanitizers isn't being friendly of multi generators, like
-G "Ninja Multi-Config" and is messing with global flags which is a no-no.
Instead it should be using a dedicated custom config IMHO.
With this change only debug will get the sanitizers, so you can for instance
build with -DCMAKE_CONFIGURATION_TYPES=Debug;RelWithDebInfo and have Debug
hardeneded with the sanitizers while the RelWithDebInfo without sanitizers,
ideal for profiling.
