scripts/functions: add a generic custom location infrastructure

Add a generic custom location infrastructure (inspired by the one in
kernel/linux) to allow the user to use custom tarballs or directories
for any component.

Signed-off-by: "David Holsgrove" <david.holsgrove@xilinx.com>
[yann.morin.1998@free.fr: move config option, improve help text, fix API doc]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-Id: <131c163c69f9cc81d2be.1349931191@localhost.localdomain>
PatchWork-Id: 190784
Message-Id: <0bbaba9190a76ba97f72.1349931192@localhost.localdomain>
PatchWork-Id: 190785

diff -dur strace-4.5.15.orig/signal.c strace-4.5.15/signal.c

--- strace-4.5.15.orig/signal.c	2007-01-11 23:08:38.000000000 +0100

+++ strace-4.5.15/signal.c	2007-07-14 19:24:43.000000000 +0200

@@ -1440,7 +1440,7 @@

 	  	tcp->u_rval = tcp->u_error = 0;

 		if(tcp->u_arg[0] == 0)

 		  	return 0;

-		tcp->auxstr = sprintsigmask("mask now ", tcp->u_arg[1]);

+		tcp->auxstr = sprintsigmask("mask now ", tcp->u_arg[1], 0);

 		return RVAL_NONE | RVAL_STR;

 	}

 	return 0;