sim: tweak load buffer type to avoid signed warnings

The sim_load_file func creates a buffer with arbitrary data in it (reads
it via the bfd).  It then passes it on to a sim_write_fn which expects a
unsigned char buffer.  Since sim_load_file itself doesn't care about the
contents, tweak the type to avoid signed mismatch warnings from gcc:

common/sim-load.c: In function ‘sim_load_file’:
common/sim-load.c:143: warning: pointer targets in passing argument 3 of ‘do_write’ differ in signedness
common/sim-load.c:143: note: expected ‘const unsigned char *’ but argument is of type ‘char *’

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

sim/common/ChangeLog

@@ -1,3 +1,7 @@
+2011-01-05  Mike Frysinger  <vapier@gentoo.org>
+
+	* sim-load.c (sim_load_file): Change buffer type to unsigned char *.
+
 2011-01-05  Joel Brobecker  <brobecker@adacore.com>
 
 	* run.1: Copyright year update.

sim/common/sim-load.c

@@ -111,7 +111,7 @@ sim_load_file (sd, myname, callback, prog, prog_bfd, verbose_p, lma_p, do_write)
 	  size = bfd_get_section_size (s);
 	  if (size > 0)
 	    {
-	      char *buffer;
+	      unsigned char *buffer;
 	      bfd_vma lma;
 
 	      buffer = malloc (size);