Add a PyInstaller spec to exclude system DLLs.

scripts/build-exe.cmd

@@ -1 +1 @@
-pyinstaller -y --onefile --additional-hooks-dir=. ../dosage
+py -m PyInstaller -y dosage.spec

scripts/dosage.spec

@@ -0,0 +1,31 @@
+# -*- mode: python -*-
+
+block_cipher = None
+
+
+a = Analysis(['../dosage'],
+             pathex=['.'],
+             binaries=[],
+             datas=[],
+             hiddenimports=[],
+             hookspath=['.'],
+             runtime_hooks=[],
+             excludes=[],
+             win_no_prefer_redirects=False,
+             win_private_assemblies=False,
+             cipher=block_cipher)
+
+a.binaries = [x for x in a.binaries if not x[1].lower().startswith(r'c:\windows')]
+
+pyz = PYZ(a.pure, a.zipped_data,
+             cipher=block_cipher)
+exe = EXE(pyz,
+          a.scripts,
+          a.binaries,
+          a.zipfiles,
+          a.datas,
+          name='dosage',
+          debug=False,
+          strip=False,
+          upx=False,
+          console=True)