support for dyld shared cache

[psifertex]

See: http://iphonedevwiki.net/index.php/Dyld_shared_cache for more info.

[cornejo]

If you need to get copies of a dyld_shared_cache_ file then you can follow the steps here (http://newosxbook.com/articles/OTA.html) to extract one for yourself from one of the updates here (https://www.theiphonewiki.com/wiki/OTA_Updates)

Note that the files taken from actual phones are a) encrypted (I believe?) and b) have some form of ASLR pre-applied to them.

[psifertex]

Blocking on #133

[brinlyau]

Apple OSS'ed their latest version of dyld, plus you could probably look at how the Ghidra loader works. https://github.com/apple-oss-distributions/dyld

[psifertex]

Thanks -- we've got some other references for this too I thought I posted on this issue but it must have been a different one. I did at least tag this for 3.3 which is when we expect to be working on it again.

[0cyn]

In the meantime, this works for arm64 shared caches: https://github.com/cxnder/bn-dyldsharedcache