Normalize source line and column numbers.

This commit adds a normalization for line and column numbers in stderr
files where the line/col is from the source directory rather than
the test itself - thereby removing the need to update tests as
compiler source changes.

Author: davidtwco

Diff for: src/test/ui/consts/const-size_of-cycle.stderr

@@ -2,13 +2,13 @@ error[E0391]: cycle detected when computing layout of `Foo`
    |
 note: ...which requires normalizing `ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: All }, value: [u8; _] }`...
 note: ...which requires const-evaluating `Foo::bytes::{{constant}}`...
-  --> $SRC_DIR/libcore/mem.rs:323:14
+  --> $SRC_DIR/libcore/mem.rs:LL:COL
    |
 LL |     unsafe { intrinsics::size_of::<T>() }
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: ...which again requires computing layout of `Foo`, completing the cycle
 note: cycle used when const-evaluating `Foo::bytes::{{constant}}`
-  --> $SRC_DIR/libcore/mem.rs:323:14
+  --> $SRC_DIR/libcore/mem.rs:LL:COL
    |
 LL |     unsafe { intrinsics::size_of::<T>() }
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^

Diff for: src/test/ui/impl-trait/impl-generic-mismatch.stderr

@@ -30,7 +30,7 @@ error[E0643]: method `hash` has incompatible signature for trait
 LL |     fn hash(&self, hasher: &mut impl Hasher) {}
    |                                 ^^^^^^^^^^^ expected generic parameter, found `impl Trait`
    | 
-  ::: $SRC_DIR/libcore/hash/mod.rs:185:13
+  ::: $SRC_DIR/libcore/hash/mod.rs:LL:COL
    |
 LL |     fn hash<H: Hasher>(&self, state: &mut H);
    |             - declaration in trait here

Diff for: src/tools/compiletest/src/runtest.rs

@@ -2963,6 +2963,13 @@ impl<'test> TestCx<'test> {
             normalized = normalized.replace("\\n", "\n");
         }
 
+        // If there are `$SRC_DIR` normalizations with line and column numbers, then replace them
+        // with placeholders as we do not want tests needing updated when compiler source code
+        // changes.
+        // eg. $SRC_DIR/libcore/mem.rs:323:14 becomes $SRC_DIR/libcore/mem.rs:LL:COL
+        normalized = Regex::new("SRC_DIR(.+):\\d+:\\d+").unwrap()
+            .replace_all(&normalized, "SRC_DIR$1:LL:COL").into_owned();
+
         normalized = normalized.replace("\\\\", "\\") // denormalize for paths on windows
               .replace("\\", "/") // normalize for paths on windows
               .replace("\r\n", "\n") // normalize for linebreaks on windows