TST: Remove numpy cpu disabling from some subprocess tests

This removes the NPY_DISABLE_CPU_FEATURES flag from the sphinx and tk tests
as they emit warnings on CI which leads to failure from the subprocess.
These don't need to be disabled on these tests, so remove them from
the environment variables that are passed in.

Author: greglucas

lib/matplotlib/tests/test_backend_tk.py

@@ -36,7 +36,8 @@ def test_func():
         try:
             proc = subprocess.run(
                 [sys.executable, "-c", f"{source}\n{func.__name__}()"],
-                env={**os.environ, "MPLBACKEND": "TkAgg"},
+                env={**os.environ, "MPLBACKEND": "TkAgg",
+                     "NPY_DISABLE_CPU_FEATURES": ""},
                 timeout=_test_timeout,
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,

lib/matplotlib/tests/test_sphinxext.py

@@ -28,7 +28,8 @@ def test_tinypages(tmpdir):
     # coverage anyways); hide them using GCOV_ERROR_FILE.
     proc = Popen(
         cmd, stdout=PIPE, stderr=PIPE, universal_newlines=True,
-        env={**os.environ, "MPLBACKEND": "", "GCOV_ERROR_FILE": os.devnull})
+        env={**os.environ, "MPLBACKEND": "", "GCOV_ERROR_FILE": os.devnull,
+             "NPY_DISABLE_CPU_FEATURES": ""})
     out, err = proc.communicate()
 
     # Build the pages with warnings turned into errors
@@ -128,7 +129,8 @@ def build_sphinx_html(source_dir, doctree_dir, html_dir, extra_args=None):
     cmd = [sys.executable, '-msphinx', '-W', '-b', 'html',
            '-d', str(doctree_dir), str(source_dir), str(html_dir), *extra_args]
     proc = Popen(cmd, stdout=PIPE, stderr=PIPE, universal_newlines=True,
-                 env={**os.environ, "MPLBACKEND": ""})
+                 env={**os.environ, "MPLBACKEND": "",
+                      "NPY_DISABLE_CPU_FEATURES": ""})
     out, err = proc.communicate()
 
     assert proc.returncode == 0, \