Make it possible to build and use ext on windows

- change ext attributes and c source for windows allowing to build pyd
 - remove trailing slashes in data_files
 - try to load pyd in proofofwork by ctypes.PyDLL()

setup.py

@@ -59,6 +59,13 @@ if __name__ == "__main__":
         libraries=['pthread', 'crypto'],
     )
 
+    if sys.platform[:3] == 'win':
+        bitmsghash.libraries = ['libeay32', 'ws2_32']
+        openssl_dir = os.getenv('OPENSSL_DIR')
+        if openssl_dir:
+            bitmsghash.library_dirs = [os.path.join(openssl_dir, 'lib')]
+            bitmsghash.include_dirs = [os.path.join(openssl_dir, 'include')]
+
     installRequires = ['six']
     packages = [
         'pybitmessage',
@@ -90,11 +97,11 @@ if __name__ == "__main__":
             packages += ['pybitmessage.fallback.umsgpack']
 
     data_files = [
-        ('share/applications/',
+        ('share/applications',
             ['desktop/pybitmessage.desktop']),
-        ('share/icons/hicolor/scalable/apps/',
+        ('share/icons/hicolor/scalable/apps',
             ['desktop/icons/scalable/pybitmessage.svg']),
-        ('share/icons/hicolor/24x24/apps/',
+        ('share/icons/hicolor/24x24/apps',
             ['desktop/icons/24x24/pybitmessage.png'])
     ]
 

src/bitmsghash/bitmsghash.cpp

@@ -163,3 +163,8 @@ extern "C" EXPORT unsigned long long BitmessagePOW(unsigned char * starthash, un
 	free(threaddata);
 	return successval;
 }
+
+// workaround for building setuptools ext on Windows
+// https://stackoverflow.com/questions/34689210
+void initbitmsghash() {} //Python 2.7
+void PyInit_bitmsghash() {} //Python 3.5

src/proofofwork.py

@@ -298,7 +298,13 @@ def init():
             bitmsglib = 'bitmsghash64.dll'
         try:
             # MSVS
-            bso = ctypes.WinDLL(os.path.join(paths.codePath(), "bitmsghash", bitmsglib))
+            libfile = os.path.join(paths.codePath(), "bitmsghash", bitmsglib)
+            if os.path.isfile(libfile):
+                bso = ctypes.WinDLL(libfile)
+            else:
+                bitmsglib = 'bitmsghash.pyd'
+                libfile = os.path.join(paths.codePath(), "bitmsghash", bitmsglib)
+                bso = ctypes.PyDLL(libfile)
             logger.info("Loaded C PoW DLL (stdcall) %s", bitmsglib)
             bmpow = bso.BitmessagePOW
             bmpow.restype = ctypes.c_ulonglong