xcbuild: fix build by adding missing include

pkgs/development/tools/xcbuild/default.nix

@@ -30,6 +30,8 @@ in stdenv.mkDerivation {
     sha256 = "1xxwg2849jizxv0g1hy0b1m3i7iivp9bmc4f5pi76swsn423d41m";
   };
 
+  patches = [ ./includes.patch ];
+
   prePatch = ''
     rmdir ThirdParty/*
     cp -r --no-preserve=all ${googletest} ThirdParty/googletest

pkgs/development/tools/xcbuild/includes.patch

@@ -0,0 +1,10 @@
+--- a/Libraries/plist/Sources/Format/Encoding.cpp
++++ b/Libraries/plist/Sources/Format/Encoding.cpp
+@@ -11,6 +11,7 @@
+ #include <plist/Format/unicode.h>
+ 
+ #include <cassert>
++#include <cstdlib> /* abort() */
+ 
+ #if defined(__linux__)
+ #include <endian.h>