remove support for BSD/OS (closes bpo-31624) (#3812)

diff --git a/Lib/distutils/util.py b/Lib/distutils/util.py
index 9394c1e..8368262 100644
--- a/Lib/distutils/util.py
+++ b/Lib/distutils/util.py
@@ -53,8 +53,8 @@
 
     (osname, host, release, version, machine) = os.uname()
 
-    # Convert the OS name to lowercase, remove '/' characters
-    # (to accommodate BSD/OS), and translate spaces (for "Power Macintosh")
+    # Convert the OS name to lowercase, remove '/' characters, and translate
+    # spaces (for "Power Macintosh")
     osname = osname.lower().replace('/', '')
     machine = machine.replace(' ', '_')
     machine = machine.replace('/', '-')
diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 8dfe1a7..9ee4d31 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -632,8 +632,8 @@
     # Try to distinguish various flavours of Unix
     osname, host, release, version, machine = os.uname()
 
-    # Convert the OS name to lowercase, remove '/' characters
-    # (to accommodate BSD/OS), and translate spaces (for "Power Macintosh")
+    # Convert the OS name to lowercase, remove '/' characters, and translate
+    # spaces (for "Power Macintosh")
     osname = osname.lower().replace('/', '')
     machine = machine.replace(' ', '_')
     machine = machine.replace('/', '-')
diff --git a/Lib/test/test_fcntl.py b/Lib/test/test_fcntl.py
index e3b7ed2..acd5c7c 100644
--- a/Lib/test/test_fcntl.py
+++ b/Lib/test/test_fcntl.py
@@ -22,7 +22,7 @@
     else:
         start_len = "qq"
 
-    if (sys.platform.startswith(('netbsd', 'freebsd', 'openbsd', 'bsdos'))
+    if (sys.platform.startswith(('netbsd', 'freebsd', 'openbsd'))
         or sys.platform == 'darwin'):
         if struct.calcsize('l') == 8:
             off_t = 'l'