go1.26.4
all: make copyright headers consistent with one space after period
test: match gofrontend error messages
cmd/compile/internal/syntax: better errors for syntax errors in lists
go/parser: adjustments to error messages
cmd/compile/internal/syntax: generalize error about var decls in init clauses
cmd/compile/internal/parser: improved syntax error for incorrect if/for/switch header
cmd/compile: better error message when offending/missing token is a keyword
cmd/compile/internal/syntax: better error when an assignment is used in value context