[mycpp/runtime cleanup] Remove Cheney GC

We're going to change the object header, and the #ifdef is just
cluttering things up.

We have a good plan for other optimizations, not moving GC!  Mainly:

- SmallStr optimization
- Boxless optimization (tagged pointers)

mycpp/NINJA_subgraph.py

@@ -18,26 +18,9 @@ def DefineTargets(ru):
       deps_base_dir = 'prebuilt/ninja',
       template = 'mycpp')
 
-  ru.cc_library(
-      '//mycpp/cheney_heap', 
-      srcs = ['mycpp/cheney_heap.cc'])
-
-  # special test with -D
-  ru.cc_binary(
-      'mycpp/cheney_heap_test.cc',
-      deps = ['//mycpp/cheney_heap'],
-      matrix = [
-        ('cxx', 'asan+cheney'),
-        ('cxx', 'ubsan+cheney'),
-        ('clang', 'ubsan+cheney'),
-        ('clang', 'coverage+cheney'),
-      ],
-      phony_prefix = 'mycpp-unit')
-
   ru.cc_library(
       '//mycpp/runtime', 
-      # TODO: separate into //mycpp/runtime_{marksweep,bumpleak,cheney}
-      deps = [ '//mycpp/cheney_heap' ],
+      # Could separate into //mycpp/runtime_{marksweep,bumpleak}
       srcs = [
         'mycpp/bump_leak_heap.cc',
         'mycpp/gc_builtins.cc',

mycpp/TEST.sh

@@ -255,12 +255,6 @@ test-runtime() {
     run-test-bin $bin
   done
 
-  for config in cxx-asan+cheney $ubsan_compiler-ubsan+cheney; do
-    local bin=_bin/$config/mycpp/cheney_heap_test
-    ninja $bin
-    run-test-bin $bin
-  done
-
   # Run other tests with all variants
 
   unit $ubsan_compiler ubsan