Removed two (!) D1/Tango runtime build systems.

As discussed on IRC, Bob has been the default (and recommended) way to build Tango for LDC for quite some time now. Support for it in the CMake-based build system just created a big maintenance burden for (almost) no benefits. Besides, the build system was currently broken anyway.

The makefiles seemed to support building *.bc libs for Tango though, which Bob probably doesn't, which might be worth keeping in mind.

runtime/README

@@ -1,30 +1,24 @@
-This should help get the runtime built.
-FOR D1:
-=======
-1) Do a checkout of tango trunk into the ldc root dir (along dmd, gen, runtime etc).
+Building druntime/Phobos for D2
+---
 
-    *   $ ls
-    *   dmd dmd2 gen ir ...
-    *   $ svn co http://svn.dsource.org/projects/tango/trunk tango
+LDC currently needs custom forks of druntime and Phobos. They are integrated
+with the main repository using Git submodules. To build them, make sure you
+have up-to-date copies of the submodules in your local repository:
 
-2) Compile the runtime
+$ git submodule update -i
 
-    *   sh build.sh
+The libraries should then be built and installed automatically along with the
+compiler itself. If, for some reason, you want to build them separately, the
+targets are:
 
-FOR D2:
-=======
-1) Check http://bitbucket.org/prokhin_alexy/ldc2/wiki/Home for up to date instructions
+$ make runtime
+$ make phobos2
 
-2) At the time of writing, this works:
 
-    *   $ git clone https://github.com/AlexeyProkhin/druntime
-    *   $ git clone https://github.com/AlexeyProkhin/phobos
+Building Tango for D1
+---
 
-3) Using cmake, set the D version to 2, then set the correct paths for druntime and phobos
-
-4) Compile ldc2, druntime, and phobos
-
-    *   $ make phobos2
-
-=======
-Enjoy!
+This directory used to contain scripts for building Tango for LDC/D1, which
+became obsolete after LDC support was added to its build system, and were
+consequently removed. Please use the official Tango build system (bob) from
+now on.