FS-5971 fix conditional compile for for windows x64

src/include/switch_platform.h

@@ -227,9 +227,10 @@ typedef intptr_t switch_ssize_t;
 
 #ifdef WIN32
 
-#ifdef WIN64
+#ifdef _WIN64
 #define SWITCH_SSIZE_T_FMT          "lld"
 #define SWITCH_SIZE_T_FMT           "lld"
+#define FS_64BIT 1
 #else
 #define SWITCH_SSIZE_T_FMT          "d"
 #define SWITCH_SIZE_T_FMT           "d"
@@ -268,7 +269,7 @@ typedef intptr_t switch_ssize_t;
 #endif
 
 
-#if UINTPTR_MAX == 0xffffffffffffffff || defined(_WIN64)
+#if UINTPTR_MAX == 0xffffffffffffffff
 #define FS_64BIT 1
 #endif