windows: Fix process termination code.

The ctrl-c hack used before didn't actually seem to work.

No haskell libraries expose TerminateProcess. I tried just calling it via
FFI, but got segfaults, probably to do with the wacky process handle not
being managed correctly. Moving it all into one C function worked.

This was hell. The EvilLinker hack was just final icing on the cake.
We all know what the cake was made of.

Build/EvilLinker.hs

@@ -17,6 +17,7 @@ import Control.Applicative ((<$>))
 import Control.Monad
 import System.Directory
 import Data.Maybe
+import Data.List
 
 import Utility.Monad
 import Utility.Process
@@ -94,13 +95,19 @@ parseCollect2 = do
 	path <- manyTill anyChar (try $ string ldcmd)
 	void $ char ' '
 	params <- restOfLine
-	return $ CmdParams (path ++ ldcmd) (escapeDosPaths params) Nothing
+	return $ CmdParams (path ++ ldcmd) (skipHack $ escapeDosPaths params) Nothing
   where
 	ldcmd = "ld.exe"
 	versionline = do
 		void $ string "collect2 version"
 		restOfLine
-	
+
+{- For unknown reasons, asking the linker to link this in fails,
+ - with error about multiple definitions of a symbol from the library.
+ - This is a horrible hack. -}
+skipHack :: String -> String
+skipHack = replace "dist/build/git-annex/git-annex-tmp/Utility/winprocess.o" ""
+
 {- Input contains something like 
  - c:/program files/haskell platform/foo -LC:/Program Files/Haskell Platform/ -L...
  - and the *right* spaces must be escaped with \