attr: inline syscall patch

Unfortunately the output of git.savannah.nongnu.org changes with each
gitweb update. This means that the current has
“0gja54fz79a9ma6b4mprnjxq77l5yg2z9xknlwhmkcrfnam02qxp” is no longer
correct:

$ nix-prefetch-url
https://git.savannah.nongnu.org/cgit/attr.git/patch/\?id=14adc898a36948267bfe5c63b399996879e94c98
1g8sky52rjg9fpmrddza1af89s9qd4bzsbxqb7mc5bv8gyh10s1k

Normally, we use fetchpatch to strip this out, but unfortunately attr
cannot use fetchpatch due to being used in bootstrapping fetchurl.
That is, it can’t use a custom postFetch since <nix/fetchurl.nix>
doesn’t support that.

To solve this problem, just inline the patch for now.

pkgs/development/libraries/attr/default.nix

@@ -14,10 +14,7 @@ stdenv.mkDerivation rec {
 
   patches = [
     # fix fakechroot: https://github.com/dex4er/fakechroot/issues/57
-    (fetchurl {
-      url = "https://git.savannah.nongnu.org/cgit/attr.git/patch/?id=14adc898a36948267bfe5c63b399996879e94c98";
-      sha256 = "0gja54fz79a9ma6b4mprnjxq77l5yg2z9xknlwhmkcrfnam02qxp";
-    })
+    ./syscall.patch
   ];
 
   postPatch = ''

pkgs/development/libraries/attr/syscall.patch

@@ -0,0 +1,120 @@
+From 14adc898a36948267bfe5c63b399996879e94c98 Mon Sep 17 00:00:00 2001
+From: Andreas Gruenbacher <agruenba@redhat.com>
+Date: Fri, 17 Aug 2018 14:07:31 +0200
+Subject: Switch back to syscall()
+
+Switch back to syscall() for the *xattr system calls.  The current
+mechanism of forwarding those calls to glibc breaks libraries like
+libfakeroot (fakeroot) and libasan (the gcc address sanitizer; gcc
+-fsanitize=address).
+
+Those libraries provide wrappers for functions defined in other shared
+libraries, usually glibc, do their own processing, and forward calls to
+the original symbols looke dup via dlsym(RTLD_NEXT, "symbol_name").  In
+our case, dlsym returns the libattr_*xattr wrappers.  However, when our
+wrappers try calling glibc, they end up calling the libfakeroot /
+libasan wrappers instead because those override the original symbols =>
+recursion.
+
+The libattr_*xattr wrappers will only be used when symbols are looked up
+at runtime (dlopen / dlsym).  Programs linking against libattr will
+directly use the glibc provided symbols.  Therefore, the slightly worse
+performance of syscall() won't affect any of the "normal" users of
+libattr.
+---
+ libattr/syscalls.c | 26 ++++++++++++++------------
+ 1 file changed, 14 insertions(+), 12 deletions(-)
+
+diff --git a/libattr/syscalls.c b/libattr/syscalls.c
+index 3013aa0..721ad7f 100644
+--- a/libattr/syscalls.c
++++ b/libattr/syscalls.c
+@@ -22,6 +22,8 @@
+ 
+ #include "config.h"
+ 
++#include <unistd.h>
++#include <sys/syscall.h>
+ #include <sys/xattr.h>
+ 
+ #ifdef HAVE_VISIBILITY_ATTRIBUTE
+@@ -31,67 +33,67 @@
+ int libattr_setxattr(const char *path, const char *name,
+ 		     void *value, size_t size, int flags)
+ {
+-	return setxattr(path, name, value, size, flags);
++	return syscall(__NR_setxattr, path, name, value, size, flags);
+ }
+ 
+ int libattr_lsetxattr(const char *path, const char *name,
+ 		      void *value, size_t size, int flags)
+ {
+-	return lsetxattr(path, name, value, size, flags);
++	return syscall(__NR_lsetxattr, path, name, value, size, flags);
+ }
+ 
+ int libattr_fsetxattr(int filedes, const char *name,
+ 		      void *value, size_t size, int flags)
+ {
+-	return fsetxattr(filedes, name, value, size, flags);
++	return syscall(__NR_fsetxattr, filedes, name, value, size, flags);
+ }
+ 
+ ssize_t libattr_getxattr(const char *path, const char *name,
+ 			 void *value, size_t size)
+ {
+-	return getxattr(path, name, value, size);
++	return syscall(__NR_getxattr, path, name, value, size);
+ }
+ 
+ ssize_t libattr_lgetxattr(const char *path, const char *name,
+ 			  void *value, size_t size)
+ {
+-	return lgetxattr(path, name, value, size);
++	return syscall(__NR_lgetxattr, path, name, value, size);
+ }
+ 
+ ssize_t libattr_fgetxattr(int filedes, const char *name,
+ 			  void *value, size_t size)
+ {
+-	return fgetxattr(filedes, name, value, size);
++	return syscall(__NR_fgetxattr, filedes, name, value, size);
+ }
+ 
+ ssize_t libattr_listxattr(const char *path, char *list, size_t size)
+ {
+-	return listxattr(path, list, size);
++	return syscall(__NR_listxattr, path, list, size);
+ }
+ 
+ ssize_t libattr_llistxattr(const char *path, char *list, size_t size)
+ {
+-	return llistxattr(path, list, size);
++	return syscall(__NR_llistxattr, path, list, size);
+ }
+ 
+ ssize_t libattr_flistxattr(int filedes, char *list, size_t size)
+ {
+-	return flistxattr(filedes, list, size);
++	return syscall(__NR_flistxattr, filedes, list, size);
+ }
+ 
+ int libattr_removexattr(const char *path, const char *name)
+ {
+-	return removexattr(path, name);
++	return syscall(__NR_removexattr, path, name);
+ }
+ 
+ int libattr_lremovexattr(const char *path, const char *name)
+ {
+-	return lremovexattr(path, name);
++	return syscall(__NR_lremovexattr, path, name);
+ }
+ 
+ int libattr_fremovexattr(int filedes, const char *name)
+ {
+-	return fremovexattr(filedes, name);
++	return syscall(__NR_fremovexattr, filedes, name);
+ }
+ 
+ #ifdef HAVE_VISIBILITY_ATTRIBUTE