Fix overly strict shadows in GCC 4.9

Fixes #86. Rename some variables so that the overly strict shadows warning
on GCC 4.9 is not triggered.

CHANGELOG.md

@@ -15,6 +15,10 @@ options. The project adheres to semantic versioning.
 * Fixed an ambiguous overload in the `parse_positional` function when an
   `initializer_list` was directly passed.
 
+### Bug Fixes
+
+* Building against GCC 4.9 was broken due to overly strict shadow warnings.
+
 ## 2.0
 
 ### Changed

include/cxxopts.hpp

@@ -902,13 +902,13 @@ namespace cxxopts
     public:
     OptionDetails
     (
-      const std::string& short_name,
-      const std::string& long_name,
+      const std::string& short_,
+      const std::string& long_,
       const String& desc,
       std::shared_ptr<const Value> val
     )
-    : m_short(short_name)
-    , m_long(long_name)
+    : m_short(short_)
+    , m_long(long_)
     , m_desc(desc)
     , m_value(val)
     , m_count(0)
@@ -1038,9 +1038,9 @@ namespace cxxopts
   class KeyValue
   {
     public:
-    KeyValue(std::string key, std::string value)
-    : m_key(std::move(key))
-    , m_value(std::move(value))
+    KeyValue(std::string key_, std::string value_)
+    : m_key(std::move(key_))
+    , m_value(std::move(value_))
     {
     }