LibCrypto: Make a better ASN.1 parser

And use it to parse RSA keys.
As a bonus, this one shouldn't be reading out of bounds or messing with
the stack (as much) anymore.

Meta/CMake/all_the_debug_macros.cmake

@@ -167,6 +167,7 @@ set(DEBUG_CPP_LANGUAGE_SERVER ON)
 set(DEBUG_AUTOCOMPLETE ON)
 set(FILE_WATCHER_DEBUG ON)
 set(SYSCALL_1_DEBUG ON)
+set(RSA_PARSE_DEBUG ON)
 
 # False positive: DEBUG is a flag but it works differently.
 # set(DEBUG ON)