linux-user: increment MAX_ARG_PAGES

There's a error When doing something like that :
find / -type f -print0 | xargs -0 echo

[ done in a arm chroot with qemu-arm and linux binfmt stuff or with
find / -type f -print0 | qemu-arm -L <path> <path>/usr/bin/xargs -0
echo ]

Doing this outsite qemu is fine. The problem was the huge number of
parameters. Increasing MAX_ARG_PAGES is fixing that.

While I was at it, I've modified linux-user/main.c to report error code
of loader_exec. It helps to debug/know what's wrong.
Signed-off-by: NArnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: NRiku Voipio <riku.voipio@iki.fi>

linux-user/main.c

@@ -2372,6 +2372,7 @@ int main(int argc, char **argv, char **envp)
     envlist_t *envlist = NULL;
     const char *argv0 = NULL;
     int i;
+    int ret;
 
     if (argc <= 1)
         usage();
@@ -2576,9 +2577,10 @@ int main(int argc, char **argv, char **envp)
     env->opaque = ts;
     task_settid(ts);
 
-    if (loader_exec(filename, target_argv, target_environ, regs,
-        info, &bprm) != 0) {
-        printf("Error loading %s\n", filename);
+    ret = loader_exec(filename, target_argv, target_environ, regs,
+        info, &bprm);
+    if (ret != 0) {
+        printf("Error %d while loading %s\n", ret, filename);
         _exit(1);
     }
 

linux-user/qemu.h

@@ -140,7 +140,7 @@ extern const char *qemu_uname_release;
  * and envelope for the new program. 32 should suffice, this gives
  * a maximum env+arg of 128kB w/4KB pages!
  */
-#define MAX_ARG_PAGES 32
+#define MAX_ARG_PAGES 33
 
 /*
  * This structure is used to hold the arguments that are