Fixed compile warning: added explicit typecast for converting -1 to an unsigned number.

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@207 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Core/Core/Src/Debugger/Debugger_SymbolMap.cpp

@@ -54,7 +54,7 @@ void Reset()
     m_VectorSymbols.clear();
 
     // 0 is an invalid entry
-    CSymbol Invalid(-1, 0, ST_FUNCTION, "Invalid");
+    CSymbol Invalid(static_cast<u32>(-1), 0, ST_FUNCTION, "Invalid");
     m_VectorSymbols.push_back(Invalid);
 }