Fix for FreeImage.h errors when building for iOS/OSX Xcode

Fix for FreeImage error when compiling on OSX for iOS (Xcode)

Problem:
"error: typedef redefinition with different types ('signed char' vs
'int32_t' (aka 'int'))
typedef signed char BOOL; "

Solution:
Use #define and #undef instead of typedef for the type definitions.

(Also fixed the line endings so you can see the changes now)