[release-branch.go1.14] all: merge master into release-branch.go1.14

a864cc7560 doc: rename HTML element IDs to avoid duplicates
fb93cd45a6 net: don't check LookupHost error in TestLookupNullByte
f770366f6d runtime: don't treat SIGURG as a bad signal
e3f2e9ac4e internal/bytealg: fix riscv64 offset names

Change-Id: I2ef0665dce7f1ade9b6c826cfd5c8eab041ff23f