Use build dir for building TensorFlow pip package

build_pip_package (executed after Bazel finishes) uses a temporary
folder which gets large (2 GB for TF 2.9).
It prefers to use `$XDG_CACHE_HOME` which we set to the temporary folder
created by Easybuild in PythonPackage but that might have only enough
space for logs etc.
As this folder is part of the build put it inside the build directory.

Author: Flamefire

easybuild/easyblocks/t/tensorflow.py

@@ -943,7 +943,10 @@ def build_step(self):
         run_cmd(' '.join(cmd), log_all=True, simple=True, log_ok=True)
 
         # run generated 'build_pip_package' script to build the .whl
-        cmd = "bazel-bin/tensorflow/tools/pip_package/build_pip_package %s" % self.builddir
+        # TF uses the temporary folder, with $XDG_CACHE_HOME taking precedence,
+        # This becomes quite large (~2 GB) so use the build folder explicitely.
+        cmd = "XDG_CACHE_HOME='%s' " % os.path.join(self.builddir, 'cache-dir')
+        cmd += "bazel-bin/tensorflow/tools/pip_package/build_pip_package %s" % self.builddir
         run_cmd(cmd, log_all=True, simple=True, log_ok=True)
 
     def test_step(self):