build: build CTensorFlow with SPM (tensorflow#1150)

* build: build `CTensorFlow` with SPM

The `CTensorFlow` module provides the C bindings for X10 and is required
for building with X10 and SPM.

* Update Dockerfile

Disable swift-models release mode build pending a fix for building Swift Numerics in release mode.

* Update Dockerfile

Remove the TensorFlow modulemap.

Dockerfile

@@ -77,7 +77,8 @@ RUN git clone https://github.com/deepmind/open_spiel.git
 WORKDIR /swift-models
 
 RUN /swift-tensorflow-toolchain/usr/bin/swift build
-RUN /swift-tensorflow-toolchain/usr/bin/swift build -c release
+# Swift Numerics in release mode does not currently build, which prevents the use of swift-models
+# RUN /swift-tensorflow-toolchain/usr/bin/swift build -c release
 
 WORKDIR /fastai_dev/swift/FastaiNotebook_11_imagenette
 
@@ -99,4 +100,5 @@ RUN rm -f /swift-tensorflow-toolchain/usr/lib/swift/linux/libswiftTensorFlow.so
 RUN python3 Utilities/benchmark_compile.py /swift-tensorflow-toolchain/usr/bin/swift benchmark_results.xml
 
 # Run SwiftPM tests
-RUN /swift-tensorflow-toolchain/usr/bin/swift test
+RUN rm -f /swift-tensorflow-toolchain/usr/lib/swift/tensorflow/module.modulemap
+RUN /swift-tensorflow-toolchain/usr/bin/swift test -Xcc -I/swift-tensorflow-toolchain/usr/lib/swift -Xlinker -L/swift-tensorflow-toolchain/usr/lib/swift/linux

Package.swift

@@ -40,11 +40,15 @@ let package = Package(
     .target(
       name: "Tensor",
       dependencies: []),
+    .target(
+      name: "CTensorFlow",
+      dependencies: []),
     .target(
       name: "TensorFlow",
       dependencies: [
         "Tensor",
         "PythonKit",
+        "CTensorFlow",
         .product(name: "Numerics", package: "swift-numerics"),
       ]),
     .target(