Drop xcode bit from the Hacking file

It's obsolete. The project file it refers to no longer
exists in the source tree. cmake can generate an
xcodeproject if anyone wants to play with it.

HACKING

@@ -124,54 +124,3 @@ for A in `find lib64 -name '*.so'`; do \
   echo -e "\n##$A requirements:" && nm $A | grep ' U ' | \
   sed 's/^.* \([^ ]*\)$/\1/' | grep -wFf- exportedsymbols | \
   cut -d: -f1 | sort | uniq; done
-
-XCode project
--------------
-
-There is an XCode project available in gnucash.xcodeproj at the root of the
-source tree.  This project can be used with XCode on a Macintosh to debug
-GnuCash.  It is not set up to build GnuCash, but only to debug it. Building must
-be done using the normal command line tools.
-
-Note this XCode project has not been updated since the big directory restructuring
-preceding the 2.7.1 release. So it will currently not find source files where
-it's expecting them.
-
-This project is designed to be used with the X Window version of GnuCash, not
-the native Quartz version.  To use it you must build and install GnuCash into
-directories "build" and "install" parallel to the source directory.  Furthermore
-the architecture dependent parts of the install are put in a subdirectory
-"install/darwin".
-
-To build, then, if the source directory is somewhere/gnucash you must create the
-directories somewhere/build/darwin and somewhere/install/darwin/bin, cd into
-somewhere/build/darwin and execute
-
-    ../../gnucash/configure --prefix=../../install \
-                            --exec-prefix=../../install/bin \
-                            --enable-debug \
-                            ...other options...
-    make
-    make install
-
-This will build and install a copy of GnuCash that can be debugged using the
-XCode project.
-
-The debug target in the project is set with a build tool of /usr/bin/true so
-building in XCode won't hurt anything, it just won't do much.  It is also set to
-not launch GnuCash automatically, but rather to wait for it to be launched
-manually. This lets you run it from a command prompt and see the console output
-which can often be useful.  Hence to initiate a debugging session in XCode, tell
-XCode to run GnuCash then go to a terminal window and launch install/darwin/bin/gnucash
-with whatever options you want.  XCode will notice that it has been launched and
-attach to the process.
-
-Since there seems to be no way to make the path to the executable a relative
-path, you must make one change to the debug scheme before you can run gnucash
-under XCode.  In XCode 5 (other versions may be different) go to
-Product->Scheme->Edit Scheme and select the "info" tab of the "Run gnucash"
-pane. Select "Other..." in the "Executable" menu and select the installed binary
-for gnucash in the resulting file open dialog.  This should be
-install/darwin/bin/gnucash as described above.  This, and the act of opening the
-project in XCode, will change some of the files in the XCode project directory.
-You can, or course, commit these locally, but please don't push them upstream.