Add tests and fixes for the two remaining issues.

This fixes the issue of unwanted changes in the following situations:

*  Space after a doc comment
*  Space before a comment in the last line of the file (without trailing
   newline)

Author: martinboehme

src/missed_spans.rs

@@ -364,11 +364,20 @@ impl<'a> FmtVisitor<'a> {
             }
         }
 
-        let remaining = snippet[status.line_start..subslice.len() + offset].trim();
-        if !remaining.is_empty() {
-            self.push_str(&self.block_indent.to_string(self.config));
-            self.push_str(remaining);
-            status.line_start = subslice.len() + offset;
+        let mut remaining = &snippet[status.line_start..subslice.len() + offset];
+        status.line_start = subslice.len() + offset;
+
+        let skip_this_line = !self
+            .config
+            .file_lines()
+            .contains_line(file_name, status.cur_line);
+        if !skip_this_line {
+            remaining = remaining.trim();
+            if !remaining.is_empty() {
+                self.push_str(&self.block_indent.to_string(self.config));
+            }
         }
+
+        self.push_str(remaining);
     }
 }

src/visitor.rs

@@ -895,8 +895,12 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
             return false;
         }
 
-        let rewrite = attrs.rewrite(&self.get_context(), self.shape());
         let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
+        if out_of_file_lines_range!(self, span) {
+            return false;
+        }
+
+        let rewrite = attrs.rewrite(&self.get_context(), self.shape());
         self.push_rewrite(span, rewrite);
 
         false

tests/source/issue-5136-4.rs

@@ -0,0 +1,4 @@
+// rustfmt-file_lines: []
+// Test that a missing space at the end of a doc comment is preserved when the
+// line is not in the --file-lines range.
+//! 

tests/source/issue-5136-5.rs

@@ -0,0 +1,6 @@
+// rustfmt-file_lines: []
+// Test that the space before the comment is not removed if the line is not
+// contained in `--file-lines`.
+// Note: It's important for the bug to repro that there is no newline at the
+// end of the comment
+fn f(){} // what

tests/target/issue-5136-4.rs

@@ -0,0 +1,4 @@
+// rustfmt-file_lines: []
+// Test that a missing space at the end of a doc comment is preserved when the
+// line is not in the --file-lines range.
+//! 

tests/target/issue-5136-5.rs

@@ -0,0 +1,6 @@
+// rustfmt-file_lines: []
+// Test that the space before the comment is not removed if the line is not
+// contained in `--file-lines`.
+// Note: It's important for the bug to repro that there is no newline at the
+// end of the comment
+fn f(){} // what