Handle Mozilla license blocks in the GN header checker.

tools/gn/c_include_iterator.cc

Index: tools/gn/c_include_iterator.cc
diff --git a/tools/gn/c_include_iterator.cc b/tools/gn/c_include_iterator.cc
index 9e719c740929b261fde2bae8e39f057feddedbdf..120295ea41650c04fe7edef6363bebc4f74b771a 100644
--- a/tools/gn/c_include_iterator.cc
+++ b/tools/gn/c_include_iterator.cc
@@ -48,6 +48,8 @@ base::StringPiece TrimLeadingWhitespace(const base::StringPiece& str) {
 bool ShouldCountTowardNonIncludeLines(const base::StringPiece& line) {
   if (StartsWith(line, "//"))
     return false;  // Don't count comments.
+  if (StartsWith(line, "/*") || StartsWith(line, " *"))
+    return false;  // C-style comment blocks with stars along the left side.
   if (StartsWith(line, "#"))
     return false;  // Don't count preprocessor.
   if (base::ContainsOnlyChars(line, base::kWhitespaceASCII))