Some compilers, including gcc and cl.exe, allow command-line
arguments to be given in a file.  On the command line, this
file is given as "@file" and may be intermixed with other
command-line arguments.  This patch adds support for @file
to the wrapper command-line tools.  The wrapper cmake macros
have been updated to use this option, in order to reduce the
length of the custom_command command lines for the wrapper tools.

Change-Id: Id24c5f662fdcc6ca437715ca6ee01b910ab60bc1