readline: remove no longer needed debug patch

packages/readline/histlib.h.patch.debug

@@ -1,11 +0,0 @@
---- ./histlib.h	2016-04-22 15:03:20.000000000 +0000
-+++ ../histlib.h	2018-03-18 19:50:23.834494092 +0000
-@@ -52,7 +52,7 @@
- 
- #ifndef member
- #  ifndef strchr
--extern char *strchr ();
-+extern char __attribute__((overloadable)) *strchr ();
- #  endif
- #define member(c, s) ((c) ? ((char *)strchr ((s), (c)) != (char *)NULL) : 0)
- #endif