Fix an assert in constrained_gsharedvt_call_setup (), mono_class_interface_offset () returns a -1 on failure, not 0.
Remove #ifdefs from MonoTrampolineType, to prevent cross-compilation problems where the cross compiler and the target runtime have different defines. Also do a sanity check at aot load time.
Add error handling to calls of mono_reflection_create_custom_attr_data_args (). Fixes part of #13435.
[sdb] Fix round tripping of vtypes with boxed fields. Fixes #12354.
Fix Syscall.readlink() for non-ascii targets

Syscall.readlink() currently returns an integer indicating the number of
bytes in the link. As buf contains chars, this value is useless if the
target contains non-ascii characters.

This commit creates a new overload which uses a byte array instead of a
StringBuilder and rewrites the old overload to return the number of chars
instead.

Fixes #11778 and #9611