picoc: Fix build with gcc15 (#513804)

--- a/interpreter.h

+++ b/interpreter.h

@@ -173,6 +173,7 @@ struct ValueType

 };

 /* function definition */

+typedef struct Value Value;         /* Needed to allow reference before definition */

 struct FuncDef

 {

     struct ValueType *ReturnType;   /* the return value type */

@@ -180,7 +181,12 @@ struct FuncDef

     int VarArgs;                    /* has a variable number of arguments after the explicitly specified ones */

     struct ValueType **ParamType;   /* array of parameter types */

     char **ParamName;               /* array of parameter names */

-    void (*Intrinsic)();            /* intrinsic call address or NULL */

+    void (*Intrinsic)(              /* intrinsic call address or NULL */

+        struct ParseState *Parser,

+        Value *ReturnValue,

+        Value **ParamArray,

+        int ArgCount

+    );

     struct ParseState Body;         /* lexical tokens of the function body if not intrinsic */

 };

@@ -610,8 +616,8 @@ void IncludeFile(Picoc *pc, char *Filename);

  * void PicocIncludeAllSystemHeaders(); */

 /* debug.c */

-void DebugInit();

-void DebugCleanup();

+void DebugInit(Picoc *pc);

+void DebugCleanup(Picoc *pc);

 void DebugCheckStatement(struct ParseState *Parser);

--- a/platform/library_unix.c

+++ b/platform/library_unix.c

@@ -1,6 +1,6 @@

 #include "../interpreter.h"

-void UnixSetupFunc()

+void UnixSetupFunc(Picoc *pc)

 {    

 }

  buildInputs = [ readline ];

  patches = [ ./gcc15-fixes.patch ];

  makeFlags = [ "CC=${stdenv.cc.targetPrefix}cc" ];

  env.NIX_CFLAGS_COMPILE = toString (