Fix support for dynamic methods in collect_method_images (). Fixes #12412.
Older versions of iOS don't have pthread_mutexattr_setpolicy_np so dynamically look up the function and fallback on failure. Fixes #12394
Fix 2.0 corlib test suite.
Update failing mobile test
[ios] Add, as a last resort, the creation of the hash based on it's type name. Needed for some API (which provides it) and the associated unit tests
Avoid direct recursion when computing the exceptions of a method.

	* exceptions.cs: When Filling the exceptions of a method make sure
	to not recurse on the methods itself as this can lead to a stackoverflow.
Refactor the Mono.Security code to use more linker friendly ways to create hash algorithms
Change code to more linker friendly ways to create MD5 and X509Chain and allow, for iOS, the creation of X509Chain without requiring CryptoConfig