Fix enable_debug's handling of false value boolean env vars (#6040)

Right now, running a Triton kernel with MLIR_ENABLE_DUMP=0 results in
the software pipeliner pass printing spurious output due to the
dumpIntermediateSteps flag that is set when MLIR_ENABLE_DUMP is neither
true nor a function value. This fix checks that the result of
isEnvValueBool's tri-state does in fact indicate that the value is not a
boolean before setting haveDump to true.

python/src/ir.cc

@@ -1,4 +1,4 @@
-#include <optional>
+#include <optional>
 #include <pybind11/functional.h>
 #include <pybind11/pybind11.h>
 #include <pybind11/stl.h>
@@ -1774,7 +1774,9 @@ void init_triton_ir(py::module &&m) {
              std::string funcToDump;
              if (!haveDump) {
                funcToDump = triton::tools::getStrEnv("MLIR_ENABLE_DUMP");
-               if (!funcToDump.empty())
+               bool isEnvValueBool =
+                   triton::tools::isEnvValueBool(funcToDump).has_value();
+               if (!funcToDump.empty() && !isEnvValueBool)
                  haveDump = true;
              }
              if (haveDump) {