internal/core/export: update via CUE_UPDATE=1 go test

CI doesn't actually enforce that `CUE_UPDATE=1 go test ./...`
result in zero git changes, as it only requires `go test ./...` to pass
and for all CI steps to result in zero git changes.

In this particular case, it seems like the export testdata diff
was only used for informational purposes and did not affect
the outcome of the test.

Update it here so that the next commits don't have this noise.

Signed-off-by: Daniel Martí <[email protected]>
Change-Id: I89ed671294cdb3339e5286e9fc5f75b6e6ff18f0
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1199520
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>

Author: mvdan

internal/core/export/testdata/main/let.txtar

@@ -916,56 +916,7 @@ diff old new
 -		}
 -	}]
 -	files: _|_ // invalid interpolation: cycle error (and 3 more errors)
--	scoped: {
--		direct: {
--			a: 1
--		}
--		embed1: {
--			a: 1
--		}
--		embed2: {
--			a: 1
--		}
--		list: {
--			a: [1]
--		}
--		listStruct: {
--			a: [{
--				a: 1
--			}]
--		}
--		listEmbed: {
--			a: [1]
--		}
--	}
--	x: "foo"
--	incomplete: {
--		a: {
--			x: _|_ // invalid interpolation: incomplete.a.x: non-concrete value string (type string)
--			run: {
--				a: string
--			}
--		}
--		b: {
--			x: _|_ // invalid interpolation: incomplete.b.x: non-concrete value string (type string)
--			run: {
--				a: string
--			}
--		}
--		c: {
--			x:  _|_ // invalid interpolation: incomplete.c.x: non-concrete value string (type string)
--			x2: _|_ // invalid interpolation: incomplete.c.x2: non-concrete value string (type string)
--			run: {
--				a: string
--			}
--			run2: {
--				a: string
--			}
--		}
--		d: {
--			x:  _|_ // invalid interpolation: incomplete.d.x: non-concrete value string (type string)
--			x2: _|_ // invalid interpolation: incomplete.d.x2: non-concrete value string (type string)
-+	comprehension: _|_ // comprehension: key value of dynamic field must be concrete, found _|_(invalid interpolation: invalid interpolation: comprehension.filepath: undefined field: name (and 1 more errors)) (and 2 more errors)
++	comprehension: _|_ // comprehension: key value of dynamic field must be concrete, found _|_(invalid interpolation: invalid interpolation: comprehension.filepath: undefined field: name) (and 1 more errors)
 +	complete: {
 +		x: "a foo z"
 +		run: {
@@ -981,59 +932,10 @@ diff old new
 +			name: "two"
 +		}
 +	}]
-+	files: _|_ // files: key value of dynamic field must be concrete, found _|_(invalid interpolation: invalid interpolation: filepath: undefined field: name (and 1 more errors)) (and 5 more errors)
-+	scoped: {
-+		direct: {
-+			a: 1
-+		}
-+		embed1: {
-+			a: 1
-+		}
-+		embed2: {
-+			a: 1
-+		}
-+		list: {
-+			a: [1]
-+		}
-+		listStruct: {
-+			a: [{
-+				a: 1
-+			}]
-+		}
-+		listEmbed: {
-+			a: [1]
-+		}
-+	}
-+	x: "foo"
-+	incomplete: {
-+		a: {
-+			x: _|_ // invalid interpolation: incomplete.a.x: non-concrete value string (type string) (and 1 more errors)
-+			run: {
-+				a: string
-+			}
-+		}
-+		b: {
-+			x: _|_ // invalid interpolation: incomplete.b.x: non-concrete value string (type string) (and 1 more errors)
-+			run: {
-+				a: string
-+			}
-+		}
-+		c: {
-+			x:  _|_ // invalid interpolation: incomplete.c.x: non-concrete value string (type string) (and 1 more errors)
-+			x2: _|_ // invalid interpolation: incomplete.c.x2: non-concrete value string (type string) (and 1 more errors)
-+			run: {
-+				a: string
-+			}
-+			run2: {
-+				a: string
-+			}
-+		}
-+		d: {
-+			x:  _|_ // invalid interpolation: incomplete.d.x: non-concrete value string (type string) (and 1 more errors)
-+			x2: _|_ // invalid interpolation: incomplete.d.x2: non-concrete value string (type string) (and 1 more errors)
- 			run: {
- 				a: string
- 			}
++	files: _|_ // files: key value of dynamic field must be concrete, found _|_(invalid interpolation: invalid interpolation: filepath: undefined field: name) (and 3 more errors)
+ 	scoped: {
+ 		direct: {
+ 			a: 1
 -- diff/value/explanation --
 Improved error messages.
 -- out/value --