Add void to function definition of FLEXConstructorsShouldRun

Classes/Utility/FLEXMacros.h

@@ -17,7 +17,7 @@
 #define FLEX_IS_TESTING() (NSClassFromString(@"XCTest") != nil)
 
 /// Whether we want the majority of constructors to run upon load or not.
-extern BOOL FLEXConstructorsShouldRun();
+extern BOOL FLEXConstructorsShouldRun(void);
 
 /// A macro to return from the current procedure if we don't want to run constructors
 #define FLEX_EXIT_IF_NO_CTORS() if (!FLEXConstructorsShouldRun()) return;