move ancient checkArity decl from Rdecl.h to Rcallbacks.c

Author: s-u

src/jri/src/Rcallbacks.c

@@ -26,7 +26,8 @@
 #ifndef checkArity
 #define checkArity               Rf_checkArity
 #endif
-#else
+void Rf_checkArity(SEXP, SEXP); /* include/Defn.h */
+#else /* in 2.6.0 re-mapped to Rf_checkArityCall so we just disable it to avoid API issues */
 #define checkArity(X,Y)
 #endif
 

src/jri/src/Rdecl.h

@@ -19,7 +19,4 @@ int  R_ReadConsole(char*, unsigned char*, int, int); /* include/Defn.h */
 int  Rf_initialize_R(int ac, char **av); /* include/Rembedded.h - exists since 2.4.0 */
 #endif /* R < 4.6.0 */
 
-/* this one is still left over */
-void Rf_checkArity(SEXP, SEXP); /* include/Defn.h */
-
 #endif /* __RDECL_H__ */