[dev.typeparams] all: merge dev.regabi (ec741b04) into dev.typeparams

Conflicts:

* src/cmd/compile/internal/gc/main.go

Merge List:

* 2020-12-22 ec741b04 [dev.regabi] all: merge master (c9fb4eb0) into dev.regabi
* 2020-12-22 acc32ea1 [dev.regabi] codereview.cfg: add config for dev.regabi
* 2020-12-22 c9fb4eb0 cmd/link: handle grouped resource sections
* 2020-12-22 c40934b3 [dev.regabi] cmd/compile: adjust one case in walkexpr
* 2020-12-22 280e7fd1 [dev.regabi] cmd/compile: only access Func method on concrete types
* 2020-12-22 51ba53f5 [dev.regabi] cmd/compile: separate misc for gc split
* 2020-12-22 572f168e [dev.regabi] cmd/compile: separate various from Main
* 2020-12-22 3b12c6dc [dev.regabi] cmd/compile: separate typecheck more cleanly
* 2020-12-22 7c8f5356 [dev.regabi] cmd/compile: separate dowidth better
* 2020-12-22 c06a354b test: trigger SIGSEGV instead of SIGTRAP in issue11656.go
* 2020-12-22 0aa9b470 cmd/pack: r command create output file if not exist
* 2020-12-22 cb28c96b [dev.regabi] cmd/compile,cmd/link: initial support for ABI wrappers
* 2020-12-22 c8610e47 [dev.regabi] cmd/compile: add ir.BasicLit to represent literals
* 2020-12-22 3512cde1 [dev.regabi] cmd/compile: stop reusing Ntype for OSLICELIT length
* 2020-12-22 2755361e [dev.regabi] cmd/compile: change noder.declNames to returns ir.Names
* 2020-12-22 301af2cb [dev.regabi] runtime/race: adjust test pattern match for ABI wrapper
* 2020-12-22 4d27c4c2 runtime: correct error handling in several FreeBSD syscall wrappers
* 2020-12-22 9b614712 cmd/pack: treat compiler's -linkobj output as "compiler object"
* 2020-12-22 306b2451 [dev.regabi] runtime: fix ABI targets in runtime.panic{Index,Slice} shims
* 2020-12-21 bc7e4d92 syscall: don't generate ptrace on iOS
* 2020-12-21 94cfeca0 [dev.regabi] cmd/compile: stop using ONONAME with Name
* 2020-12-21 cb4898a7 [dev.regabi] cmd/compile: simplify declaration importing
* 2020-12-21 06915ac1 [dev.regabi] cmd/compile: move itabname call out of implements
* 2020-12-21 6cff874c runtime/metrics: add Read examples
* 2020-12-21 8438a577 runtime: use _exit on darwin
* 2020-12-21 cb95819c runtime: detect netbsd netpoll overrun in sysmon
* 2020-12-21 53c984d9 runtime: skip wakep call in wakeNetPoller on Plan 9
* 2020-12-21 9abbe277 test: skip issue11656.go on mips/mips64/ppc64

Change-Id: Ia12a1892195f5e08bb41465374124c71a1a135f6