Support PCAN interface on cygwin

Unfortunately, cygwin has no winreg module, so we have to use cygwinreg
instead.

can/interfaces/pcan/basic.py

@@ -17,6 +17,8 @@
 
 if platform.system() == "Windows":
     import winreg
+elif 'CYGWIN' in platform.system():
+    import cygwinreg as winreg
 
 
 logger = logging.getLogger("can.pcan")
@@ -535,7 +537,7 @@ class PCANBasic:
 
     def __init__(self):
         # Loads the PCANBasic.dll and checks if driver is available
-        if platform.system() == "Windows":
+        if platform.system() == "Windows" or "CYGWIN" in platform.system():
             self.__m_dllBasic = windll.LoadLibrary("PCANBasic")
             aReg = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
             try:

setup.py

@@ -109,6 +109,7 @@
         "filelock",
         "mypy_extensions >= 0.4.0, < 0.5.0",
         'pywin32;platform_system=="Windows"',
+        'cygwinreg;sys_platform=="cygwin"',
     ],
     setup_requires=pytest_runner,
     extras_require=extras_require,