Fix regression that omitted -DNDEBUG in opt builds after toolchain refactoring.

Not adding -DNDEBUG leads to enabling assertions which makes LLVM often 10x slower.

PiperOrigin-RevId: 317349500
Change-Id: I52df6ab5013ad5a02101dd96f18220e054c3e94c

third_party/gpus/crosstool/cc_toolchain_config.bzl.tpl

@@ -583,7 +583,11 @@ def _features(cpu, compiler, ctx):
                     ),
                 ],
             ),
-            feature(name = "opt"),
+            feature(name = "disable-assertions"),
+            feature(
+                name = "opt",
+                implies = ["disable-assertions"],
+            ),
             feature(name = "fastbuild"),
             feature(name = "dbg"),
             feature(name = "supports_dynamic_linker", enabled = True),