pkg/path: add missing param declaration

The standard library function path.Match requires 3 parameters, but only
2 are currently declared. This causes valid usage of the function to
fail with the following error:

    too many arguments in call to path.Match (have 3, want 2):

To fix this, the missing parameter declaration is added.

Fixes #3203.

Signed-off-by: Noam Dolovich <noam.tzvi.dolovich@gmail.com>
Change-Id: I6e645293f8e589ad1834e3c33ff7bffc2abb5aed
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1195888
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>

pkg/path/pkg.go

@@ -122,6 +122,7 @@ var p = &pkg.Package{
 	}, {
 		Name: "Match",
 		Params: []pkg.Param{
+			{Kind: adt.StringKind},
 			{Kind: adt.StringKind},
 			{Kind: adt.StringKind, Value: unixDefault},
 		},

pkg/path/testdata/os.txtar

@@ -56,6 +56,15 @@ Clean: [_]: {
     #"c:\abc\def\..\.."#: _
 }
 
+Match: [OS=#AnyOS]: [Pattern=string]: [Name=string]: path.Match(Pattern, Name, OS)
+Match: default: [Pattern=string]: [Name=string]: path.Match(Pattern, Name)
+Match: default: Match.unix
+Match: [_]: {
+    "*c":    "abc":               _
+    "*.txt": "a/b.txt":           _
+    "*.zip": #"c:\a\b\file.zip"#: _
+}
+
 Slash: [OS=string]: [ARG=string]: {
     to:   path.ToSlash(ARG, OS)
     from: path.FromSlash(ARG, OS)
@@ -214,6 +223,52 @@ Clean: {
 		"c:\\abc\\def\\..\\..": "c:\\"
 	}
 }
+Match: {
+	default: {
+		"*c": {
+			abc: true
+		}
+		"*.txt": {
+			"a/b.txt": false
+		}
+		"*.zip": {
+			"c:\\a\\b\\file.zip": true
+		}
+	}
+	unix: {
+		"*c": {
+			abc: true
+		}
+		"*.txt": {
+			"a/b.txt": false
+		}
+		"*.zip": {
+			"c:\\a\\b\\file.zip": true
+		}
+	}
+	plan9: {
+		"*c": {
+			abc: true
+		}
+		"*.txt": {
+			"a/b.txt": false
+		}
+		"*.zip": {
+			"c:\\a\\b\\file.zip": true
+		}
+	}
+	windows: {
+		"*c": {
+			abc: true
+		}
+		"*.txt": {
+			"a/b.txt": true
+		}
+		"*.zip": {
+			"c:\\a\\b\\file.zip": false
+		}
+	}
+}
 Slash: {
 	unix: {
 		"": {