Add back C++11 compile time check

Author: leg0

api/String.cpp

@@ -63,6 +63,7 @@ String::String(const __FlashStringHelper *pstr)
 	*this = pstr;
 }
 
+#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
 String::String(String &&rval)
 	: buffer(rval.buffer)
 	, capacity(rval.capacity)
@@ -72,6 +73,7 @@ String::String(String &&rval)
 	rval.capacity = 0;
 	rval.len = 0;
 }
+#endif
 
 String::String(char c)
 {
@@ -211,6 +213,7 @@ String & String::copy(const __FlashStringHelper *pstr, unsigned int length)
 	return *this;
 }
 
+#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
 void String::move(String &rhs)
 {
 	if (this != &rhs)
@@ -226,6 +229,7 @@ void String::move(String &rhs)
 		rhs.capacity = 0;
 	}
 }
+#endif
 
 String & String::operator = (const String &rhs)
 {
@@ -237,11 +241,13 @@ String & String::operator = (const String &rhs)
 	return *this;
 }
 
+#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
 String & String::operator = (String &&rval)
 {
 	move(rval);
 	return *this;
 }
+#endif
 
 String & String::operator = (const char *cstr)
 {

api/String.h

@@ -72,7 +72,9 @@ class String
 	String(const uint8_t *cstr, unsigned int length) : String((const char*)cstr, length) {}
 	String(const String &str);
 	String(const __FlashStringHelper *str);
+#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
 	String(String &&rval);
+#endif
 	explicit String(char c);
 	explicit String(unsigned char, unsigned char base=10);
 	explicit String(int, unsigned char base=10);
@@ -96,7 +98,9 @@ class String
 	String & operator = (const String &rhs);
 	String & operator = (const char *cstr);
 	String & operator = (const __FlashStringHelper *str);
+#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
 	String & operator = (String &&rval);
+#endif
 
 	// concatenate (works w/ built-in types)
 
@@ -227,7 +231,9 @@ class String
 	// copy and move
 	String & copy(const char *cstr, unsigned int length);
 	String & copy(const __FlashStringHelper *pstr, unsigned int length);
+#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
 	void move(String &rhs);
+#endif
 };
 
 class StringSumHelper : public String