[release-branch.go1.17] all: merge master (5805efc7) into release-branch.go1.17

Merge List:

+ 2021-08-12 5805efc7 doc/go1.17: remove draft notice
+ 2021-08-12 39634e7d CONTRIBUTORS: update for the Go 1.17 release
+ 2021-08-12 095bb790 os/exec: re-enable LookPathTest/16
+ 2021-08-11 dea23e9c src/make.*: make --no-clean flag a no-op that prints a warning
+ 2021-08-11 d4c0ed26 doc/go1.17: linker passes -I to extld as -Wl,--dynamic-linker
+ 2021-08-10 1f9c9d85 doc: use "high address/low address" instead of "top/bottom"
+ 2021-08-09 f1dce319 cmd/go: with -mod=vendor, don't panic if there are duplicate requirements
+ 2021-08-09 7aeaad5c runtime/cgo: when using msan explicitly unpoison cgoCallers
+ 2021-08-08 507cc341 doc: add example for conversion from slice expressions to array ptr
+ 2021-08-07 891547e2 doc/go1.17: fix a typo introduced in CL 335135
+ 2021-08-06 8eaf4d16 make.bash: do not overwrite GO_LDSO if already set
+ 2021-08-06 63b968f4 doc/go1.17: clarify Modules changes
+ 2021-08-06 70546f64 runtime: allow arm64 SEH to be called if illegal instruction
+ 2021-08-05 fd45e267 runtime: warn that KeepAlive is not an unsafe.Pointer workaround
+ 2021-08-04 6e738868 net/http: speed up and deflake TestCancelRequestWhenSharingConnection
+ 2021-08-02 8a7ee4c5 io/fs: don't use absolute path in DirEntry.Name doc

Change-Id: Ie9ce48bf4e99457cde966c5f972b04140468fcf0