Incorrect span when encountering incorrect opening delimiter in macro fragments

[estebank]

When writing a macro rule that tries to accept a () after a path, we correctly inform the user that ( cannot come after a path, but we point at the following character:

error: `$p:path` is followed by `(`, which is not allowed for `path` fragments
  --> $DIR/macro-follow.rs:104:15
   |
LL |     ($p:path ()) => {};
   |               ^

This is probably an off-by-one error in the span assignment of the tokens.

[estebank]

Fixed:

error: `$p:path` is followed by `(`, which is not allowed for `path` fragments
 --> src/lib.rs:2:14
  |
2 |     ($p:path ()) => {};
  |              ^ not allowed after `path` fragments
  |
  = note: allowed there are: `{`, `[`, `=>`, `,`, `>`, `=`, `:`, `;`, `|`, `as` or `where`