swift234

SIL Serialization: handle SILVTable.

We add two records in sil_block to specify a Vtable and its entry list. Two
records are also added in sil_index_block for mapping from name to ID and
from ID to bit offset.

Two functions are added to SerializedSILLoader: to look up a specific VTable
given the class name or to deserialize all VTables in all SILModules. The latter
is mostly used for testing.

We serialize a VTable if the class is fragile and deserialize it via
SerializedSILLoader::lookupVTable.


Swift SVN r9746