Don't write temp files to root directory of C: drive

Used code example from
http://msdn.microsoft.com/en-us/library/windows/desktop/aa363875.aspx
Allow backslashes in file name when running under Windows

extract_args interprets all backslashes as the beginning of an escape
sequence, but when running under Windows backslashes are valid
characters in a file name. This change makes it so that extract_args
doesn't try interpreting backslashes as escape sequences until after a
filename has been parsed.