Fix handling of _ZLXX.

Mangled names of the form _ZLXX, where XX is a number is now properly
demangled.

Test: Ran new unit tests.
Change-Id: I89fbb36d2294c46da428c75bd1a2f39f69ac4b43
diff --git a/demangle/Demangler.cpp b/demangle/Demangler.cpp
index 1b7406d..c0a96aa 100644
--- a/demangle/Demangler.cpp
+++ b/demangle/Demangler.cpp
@@ -698,6 +698,8 @@
 
   if (std::isdigit(*name)) {
     name = GetStringFromLength(name, &function_name_);
+  } else if (*name == 'L' && std::isdigit(name[1])) {
+    name = GetStringFromLength(name + 1, &function_name_);
   } else {
     name = AppendOperatorString(name);
     function_name_ = cur_state_.str;