(testsuite) Use File::Path instead of HTML::Parser to test perldoc.

HTML::Parser is not a "core" Perl module.

test/lib/completions/perldoc.exp

@@ -18,15 +18,15 @@ sync_after_int
 
 
 set test "perldoc should complete word containing colons"
-set cmd "perldoc HTML::"
+set cmd "perldoc File::"
 send "$cmd\t"
 expect {
-    # Assuming the module `HTML::Parser' is always installed
-    -re "\\sParser\\s" { pass "$test" }
+    # Assuming the module `File::Path' is always installed
+    -re "\\sPath\\s" { pass "$test" }
     # Assuming there's no perl module named `fixtures', but only our directory
     # `test/fixtures' which is presented falsely.
     -re "\\sfixtures/\\s" { fail "$test" }
-    -re "perldoc HTML::HTML::" { fail "$test" }
+    -re "perldoc File::File::" { fail "$test" }
     -re /@ { unresolved "$test" }
     default { unresolved "$test" }
 }; # expect