Don't report configure errors to CDash for successful packages (#23286)

Convert configure errors detected by our log scraper into warnings when
the package being installed reports that it was successful.

var/spack/repos/builtin.mock/packages/configure-warning/package.py

@@ -0,0 +1,33 @@
+# Copyright 2013-2021 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+
+
+class ConfigureWarning(AutotoolsPackage):
+    """This package prints output that looks like an error during configure, but
+       it actually installs successfully."""
+
+    homepage = "http://www.example.com"
+    url      = "http://www.example.com/configure-warning-1.0.tar.gz"
+
+    version('1.0', '0123456789abcdef0123456789abcdef')
+
+    parallel = False
+
+    def autoreconf(self, spec, prefix):
+        pass
+
+    def configure(self, spec, prefix):
+        print('foo: No such file or directory')
+        return 0
+
+    def build(self, spec, prefix):
+        pass
+
+    def install(self, spec, prefix):
+        # sanity_check_prefix requires something in the install directory
+        # Test requires overriding the one provided by `AutotoolsPackage`
+        mkdirp(prefix.bin)