Upgrade golang.org/x/sys/unix so that it contains go.dev/cl/419915, a
fix for FreeBSD's ptrace functions that used *byte to represent
addresses on the tracee address space.
* proc,locspec: support setting breakpoints by func name on generic funcs
Changes proc.Function to parse function names correctly when they
contain instantiation lists and locspec to match generic functions.
* vendor: update golang.org/x/tools
The old version of golang.org/x/tools is incompatible with the new
iexport format.
