Document the column numbers for the dbg! macro

The line numbers were also made consistent, some examples used the line numbers as shown on the playground while others used the line numbers that you would expect when just seeing the documentation.
The second option was chosen to make everything consistent.

library/std/src/macros.rs

@@ -230,7 +230,7 @@ macro_rules! eprintln {
 /// ```rust
 /// let a = 2;
 /// let b = dbg!(a * 2) + 1;
-/// //      ^-- prints: [src/main.rs:2] a * 2 = 4
+/// //      ^-- prints: [src/main.rs:2:9] a * 2 = 4
 /// assert_eq!(b, 5);
 /// ```
 ///
@@ -281,7 +281,7 @@ macro_rules! eprintln {
 /// This prints to [stderr]:
 ///
 /// ```text,ignore
-/// [src/main.rs:4] n.checked_sub(4) = None
+/// [src/main.rs:2:22] n.checked_sub(4) = None
 /// ```
 ///
 /// Naive factorial implementation:
@@ -301,15 +301,15 @@ macro_rules! eprintln {
 /// This prints to [stderr]:
 ///
 /// ```text,ignore
-/// [src/main.rs:3] n <= 1 = false
-/// [src/main.rs:3] n <= 1 = false
-/// [src/main.rs:3] n <= 1 = false
-/// [src/main.rs:3] n <= 1 = true
-/// [src/main.rs:4] 1 = 1
-/// [src/main.rs:5] n * factorial(n - 1) = 2
-/// [src/main.rs:5] n * factorial(n - 1) = 6
-/// [src/main.rs:5] n * factorial(n - 1) = 24
-/// [src/main.rs:11] factorial(4) = 24
+/// [src/main.rs:2:8] n <= 1 = false
+/// [src/main.rs:2:8] n <= 1 = false
+/// [src/main.rs:2:8] n <= 1 = false
+/// [src/main.rs:2:8] n <= 1 = true
+/// [src/main.rs:3:9] 1 = 1
+/// [src/main.rs:7:9] n * factorial(n - 1) = 2
+/// [src/main.rs:7:9] n * factorial(n - 1) = 6
+/// [src/main.rs:7:9] n * factorial(n - 1) = 24
+/// [src/main.rs:9:1] factorial(4) = 24
 /// ```
 ///
 /// The `dbg!(..)` macro moves the input: