Deprecate bcppcompiler.

Support for Borland C++ compiler was dropped for compiling Python in python/cpython#66782 (2014) and the borlandc.org web site no longer references a compiler. Best I can tell, this compiler hasn't been released for 22 years. Surely no one is using it.

distutils/bcppcompiler.py

@@ -13,6 +13,8 @@
 
 
 import os
+import warnings
+
 from distutils.errors import (
     DistutilsExecError,
     CompileError,
@@ -26,6 +28,14 @@
 from distutils import log
 
 
+warnings.warn(
+    "bcppcompiler is deprecated and slated to be removed "
+    "in the future. Please discontinue use or file an issue "
+    "with pypa/distutils describing your use case.",
+    DeprecationWarning,
+)
+
+
 class BCPPCompiler(CCompiler):
     """Concrete class that implements an interface to the Borland C/C++
     compiler, as defined by the CCompiler abstract class.

pytest.ini

@@ -22,5 +22,5 @@ filterwarnings=
 	ignore:The frontend.OptionParser class will be replaced by a subclass of argparse.ArgumentParser in Docutils 0.21 or later.:DeprecationWarning:
 	ignore: The frontend.Option class will be removed in Docutils 0.21 or later.:DeprecationWarning:
 
-	# suppress warnings in deprecated msvc compilers
-	ignore:msvc9?compiler is deprecated
+	# suppress warnings in deprecated compilers
+	ignore:(bcpp|msvc9?)compiler is deprecated