[build] Assorted toolchain build fixes.

- Improve TensorFlow macOS preset organization. Move things to the base preset.
- Install Python/TensorFlow in the correct location.

Author: dan-zheng

utils/build-presets.ini

@@ -2383,6 +2383,11 @@ swift-primary-variant-arch=x86_64
 enable-tensorflow
 install-tensorflow
 
+tensorflow-swift-apis
+install-tensorflow-swift-apis
+pythonkit
+install-pythonkit
+
 [preset: tensorflow_osx]
 mixin-preset=tensorflow_osx_base
 test
@@ -2393,9 +2398,6 @@ stress-test
 
 [preset: tensorflow_osx,no_test]
 mixin-preset=tensorflow_osx_base
-tensorflow-swift-apis
-pythonkit
-install-pythonkit
 skip-test-cmark
 skip-test-swift
 skip-test-swiftpm
@@ -2408,9 +2410,6 @@ skip-test-playgroundsupport
 mixin-preset=
     tensorflow_osx
     mixin_codesigning
-tensorflow-swift-apis
-pythonkit
-install-pythonkit
 darwin-toolchain-installer-package=%(darwin_toolchain_installer_package)s
 
 [preset: tensorflow_osx,no_test,installer]

utils/swift_build_support/swift_build_support/products/pythonkit.py

@@ -53,7 +53,7 @@ def build(self, host_target):
                 '-G', 'Ninja',
                 '-D', 'BUILD_SHARED_LIBS=YES',
                 '-D', 'CMAKE_INSTALL_PREFIX={}/usr'.format(
-                    self.args.install_destdir),
+                    self.install_toolchain_path()),
                 '-D', 'CMAKE_MAKE_PROGRAM={}'.format(self.toolchain.ninja),
                 '-D', 'CMAKE_Swift_COMPILER={}'.format(swiftc),
                 '-B', self.build_dir,

utils/swift_build_support/swift_build_support/products/tensorflow.py

@@ -67,7 +67,7 @@ def build(self, host_target):
                 '-G', 'Ninja',
                 '-D', 'BUILD_SHARED_LIBS=YES',
                 '-D', 'CMAKE_INSTALL_PREFIX={}/usr'.format(
-                    self.args.install_destdir),
+                    self.install_toolchain_path()),
                 '-D', 'CMAKE_MAKE_PROGRAM={}'.format(self.toolchain.ninja),
                 '-D', 'CMAKE_Swift_COMPILER={}'.format(swiftc),
                 # SWIFT_ENABLE_TENSORFLOW