C++: Update query to latest spec.

cpp/ql/src/Summary/LinesOfCode.ql

@@ -1,11 +1,11 @@
 /**
  * @id cpp/summary/lines-of-code
  * @name Total lines of C/C++ code in the database.
- * @description The total number of lines of C/C++ code across all files, including system headers and libraries. This is a useful metric of the size of a database.
+ * @description The total number of lines of C/C++ code across all files, including system headers, libraries and auto-generated files. This is a useful metric of the size of a database. Lines of code are all lines in a file that was seen during the build that contain code, i.e. are not whitespace or comments.
  * @kind metric
  * @tags summary
  */
 
 import cpp
 
-select sum(File f | f.fromSource() | f.getMetrics().getNumberOfLines())
+select sum(File f | f.fromSource() | f.getMetrics().getNumberOfLinesOfCode())

cpp/ql/test/query-tests/Summary/LinesOfCode.expected

@@ -1 +1 @@
-| 122 |
+| 93 |

cpp/ql/test/query-tests/Summary/empty-file.cpp

@@ -0,0 +1 @@
+

cpp/ql/test/query-tests/Summary/large-file.cpp

@@ -26,10 +26,14 @@ int a06(float x) {
     return (int)x;
 }
 
+/**
+ * This is a multi-line comment
+ */
 int a07(float x) {
     return (int)x;
 }
 
+// this is a single-line comment
 int a08(float x) {
     return (int)x;
 }