Common: Remove dead platform #ifdefs to make the code more readable.

Symbian, Xbox, Blackberry and iOS got removed.
FreeBSD and Android kept due to them potentially being able to run Citra in the future.
The iOS specific part also got removed from PPSSPP in order to fix a bug there.

src/common/mem_arena.h

@@ -21,10 +21,6 @@
 #include <windows.h>
 #endif
 
-#ifdef __SYMBIAN32__
-#include <e32std.h>
-#endif
-
 #include "common/common.h"
 
 // This class lets you create a block of anonymous RAM, and then arbitrarily map views into it.
@@ -39,12 +35,8 @@ public:
     void *CreateView(s64 offset, size_t size, void *base = 0);
     void ReleaseView(void *view, size_t size);
 
-#ifdef __SYMBIAN32__
-    RChunk* memmap;
-#else
     // This only finds 1 GB in 32-bit
     static u8 *Find4GBBase();
-#endif
 private:
 
 #ifdef _WIN32