Disable ninja by default (microsoft#5194)

microsoft#5192 reports an issue with the latest DeepSpeed release (0.13.3)
related to pre-compilation and the recently re-enabled `ninja` support
in microsoft#5088. Reverting to disabling `ninja` by default, but users can still
enable it with `DS_ENABLE_NINJA=1` until we can further debug to
understand the problem.

.github/workflows/nv-pre-compile-ops.yml

@@ -36,7 +36,7 @@ jobs:
             #python -c "import torch; print('CUDA available:', torch.cuda.is_available())"
         - name: Compile DeepSpeed Ops
           run: |
-            TORCH_CUDA_ARCH_LIST="7.0;7.5;8.0" DS_BUILD_OPS=1 DS_BUILD_SPARSE_ATTN=0  DS_BUILD_CUTLASS_OPS=0 DS_BUILD_RAGGED_DEVICE_OPS=0 DS_BUILD_EVOFORMER_ATTN=0 pip3 install .
+            DS_ENABLE_NINJA=1 TORCH_CUDA_ARCH_LIST="7.0;7.5;8.0" DS_BUILD_OPS=1 DS_BUILD_SPARSE_ATTN=0  DS_BUILD_CUTLASS_OPS=0 DS_BUILD_RAGGED_DEVICE_OPS=0 DS_BUILD_EVOFORMER_ATTN=0 pip3 install .
         - name: DS Report
           run: |
              ds_report

setup.py

@@ -119,7 +119,7 @@ def get_env_if_set(key, default: typing.Any = ""):
 # For any pre-installed ops force disable ninja.
 if torch_available:
     from accelerator import get_accelerator
-    use_ninja = not is_env_set("DS_DISABLE_NINJA")
+    use_ninja = is_env_set("DS_ENABLE_NINJA")
     cmdclass['build_ext'] = get_accelerator().build_extension().with_options(use_ninja=use_ninja)
 
 if torch_available: