Fix X360 Crossplay (#26)

^Reviewed-on: #26

Co-authored-by: qloak <realminecart@gmail.com>

Minecraft.Client/PS3/Leaderboards/base64.cpp

@@ -1,7 +1,7 @@
 /* 
    base64.cpp and base64.h
 
-   Copyright (C) 2004-2008 René Nyffenegger
+   Copyright (C) 2004-2008 René Nyffenegger
 
    This source code is provided 'as-is', without any express or implied
    warranty. In no event will the author be held liable for any damages
@@ -21,7 +21,7 @@
 
    3. This notice may not be removed or altered from any source distribution.
 
-   René Nyffenegger rene.nyffenegger@adp-gmbh.ch
+   René Nyffenegger rene.nyffenegger@adp-gmbh.ch
 
 */
 
@@ -41,7 +41,7 @@ static inline bool is_base64(unsigned char c) {
 }
 
 // 4J ADDED,
-std::string base64_encode(std::string str)
+std::string base64_encode(const std::string& str)
 {
 	return base64_encode( reinterpret_cast<const unsigned char*>(str.c_str()), str.length() );
 }