win32: Fix handling of long command lines (#816)

win32: Fix handling of long command lines (#816)

What is broken: handling of "execute" with long command parameters (see win32execute).

In more details:

* parameter lpCommandLine was formatted incorrectly (it has to contain app name too)
* temporary file with parameters to the compiler was formatted incorrectly (it
  should NOT contain app name; if it contains backslashes, then these
  backslashes need to be escaped as double-backslashes)
* wrong location (directory) of temporary files in win32execute
* premature deletion of temporary files in win32execute