Suppress gcc 4.x -Wpointer-sign (included in -Wall) warnings

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5275 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/exec.c b/exec.c
index c927fbc..31374da 100644
--- a/exec.c
+++ b/exec.c
@@ -1418,7 +1418,7 @@
 #if !defined(CONFIG_SOFTMMU)
         /* must avoid mmap() usage of glibc by setting a buffer "by hand" */
         {
-            static uint8_t logfile_buf[4096];
+            static char logfile_buf[4096];
             setvbuf(logfile, logfile_buf, _IOLBF, sizeof(logfile_buf));
         }
 #else