cmd/compile/internal/syntax: rename test file to match issue
Follow-up on CL 565518 which addressed issue #65790 but added
testdata/issue65970.go instead of testdata/issue65790.go.
Rename that file to match the issue.
For #65790.
Change-Id: I647c297286355137fa950fb6722e31ae4340393b
Reviewed-on: https://go-review.googlesource.com/c/go/+/567875 Reviewed-by: Robert Griesemer <gri@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
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