Merge List:
* 2020-12-22
c9fb4eb0a2 cmd/link: handle grouped resource sections
* 2020-12-22
c06a354bcc test: trigger SIGSEGV instead of SIGTRAP in issue11656.go
* 2020-12-22
0aa9b4709a cmd/pack: r command create output file if not exist
* 2020-12-22
4d27c4c223 runtime: correct error handling in several FreeBSD syscall wrappers
* 2020-12-22
9b6147120a cmd/pack: treat compiler's -linkobj output as "compiler object"
* 2020-12-21
bc7e4d9257 syscall: don't generate ptrace on iOS
* 2020-12-21
6cff874c47 runtime/metrics: add Read examples
* 2020-12-21
8438a5779b runtime: use _exit on darwin
* 2020-12-21
cb95819cf6 runtime: detect netbsd netpoll overrun in sysmon
* 2020-12-21
53c984d976 runtime: skip wakep call in wakeNetPoller on Plan 9
* 2020-12-21
9abbe27710 test: skip issue11656.go on mips/mips64/ppc64
Change-Id: Ibb235fbf6a86ebcf50c686dc11f7c02d1865f845