Change the __canonicalize_funcptr_for_compare() implementation to stop

Change the __canonicalize_funcptr_for_compare() implementation to stop
trying to read a branch instruction and decode it to extract the address
of the ld.so resolver function.  Instead, directly execute that branch
instruction.

This is effectively a C runtime ABI change.  In order to cross this if
you are building from source, make sure you install an updated ld.so
first.

ok deraadt@