Get rid of the HAVE_PROTOTYPES configuration option, as well as the related JMETHOD and JPP macros. libjpeg-turbo has never supported compilers that don't handle prototypes. Doing so requires ansi2knr, which isn't even supported in the IJG code anymore.

jdatadst.c

@@ -23,8 +23,8 @@
 #include "jerror.h"
 
 #ifndef HAVE_STDLIB_H           /* <stdlib.h> should declare malloc(),free() */
-extern void * malloc JPP((size_t size));
-extern void free JPP((void *ptr));
+extern void * malloc (size_t size);
+extern void free (void *ptr);
 #endif