Fix the MacOS FindPython build issue. (#14233)

Nanobind requires the use of FindPython. We use FindPython3 everywhere
else. They are disjoint for reasons no one knows. Empirically,
co-initializing both at the top level makes things consistent for
multi-python setups that are sensitive to such things (such as MacOS,
which will often latch FindPython differently).

Also adds an STL include header that was breaking the MacOS intel build.

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d65eb3b..d371378 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -617,10 +617,22 @@
   # seems to be robust generally.
   # See: https://reviews.llvm.org/D118148
   # If building Python packages, we have a hard requirement on 3.8+.
-  find_package(Python3 3.8 COMPONENTS Interpreter Development)
-  find_package(Python3 3.8 COMPONENTS Interpreter Development.Module REQUIRED)
+  find_package(Python3 3.8 COMPONENTS Interpreter Development NumPy)
+  find_package(Python3 3.8 COMPONENTS Interpreter Development.Module NumPy REQUIRED)
+  # Some parts of the build use FindPython instead of FindPython3. Why? No
+  # one knows, but they are different. So make sure to bootstrap this one too.
+  # Not doing this here risks them diverging, which on multi-Python systems,
+  # can be troublesome. Note that nanobind requires FindPython.
+  set(Python_EXECUTABLE "${Python3_EXECUTABLE}")
+  find_package(Python 3.8 COMPONENTS Interpreter Development.Module NumPy REQUIRED)
 elseif(IREE_BUILD_COMPILER OR IREE_BUILD_TESTS)
   find_package(Python3 COMPONENTS Interpreter REQUIRED)
+  set(Python_EXECUTABLE "${Python3_EXECUTABLE}")
+  find_package(Python COMPONENTS Interpreter REQUIRED)
+endif()
+
+if(NOT "${Python_EXECUTABLE}" STREQUAL "${Python3_EXECUTABLE}")
+  message(WARNING "FindPython and FindPython3 found different executables. You may need to pin -DPython_EXECUTABLE and -DPython3_EXECUTABLE (${Python_EXECUTABLE} vs ${Python3_EXECUTABLE})")
 endif()
 
 # Extended Python environment checks.

runtime/bindings/python/CMakeLists.txt

diff --git a/runtime/bindings/python/CMakeLists.txt b/runtime/bindings/python/CMakeLists.txt
index 8f4bac8..0b1eb2d 100644
--- a/runtime/bindings/python/CMakeLists.txt
+++ b/runtime/bindings/python/CMakeLists.txt
@@ -5,8 +5,6 @@
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 if(NOT nanobind_FOUND)
-  # nanobind requires Python >= 3.8.
-  find_package(Python 3.8 COMPONENTS Interpreter Development.Module NumPy REQUIRED)
   find_package(nanobind CONFIG QUIET)
   if(NOT nanobind_FOUND)
     execute_process(

runtime/bindings/python/invoke.cc

diff --git a/runtime/bindings/python/invoke.cc b/runtime/bindings/python/invoke.cc
index cafa2ad..2a69d00 100644
--- a/runtime/bindings/python/invoke.cc
+++ b/runtime/bindings/python/invoke.cc
@@ -7,6 +7,7 @@
 #include "./invoke.h"
 
 #include <functional>
+#include <unordered_map>
 
 #include "./hal.h"
 #include "./vm.h"