vl.c: In qemu -h output, only print options for the arch we are running as

Only print options in the help output that are accepted by our arch.
This is less confusing for users and also for other programs that
consume the help output.

The options affected are:

 -g and -prom-env only displayed on PPC or SPARC

 -win2k-hack, -rtc-td-hack, -no-fd-bootchk, -no-acpi, -no-hpet,
 -acpitable, -smbios only displayed on i386

 -semihosting only displayed on ARM, M68K or XTENSA

 -old-param only displayed on ARM

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/vl.c b/vl.c
index 25ec37b..da69f94 100644
--- a/vl.c
+++ b/vl.c
@@ -1492,24 +1492,21 @@
 
 static void help(int exitcode)
 {
-    const char *options_help =
+    version();
+    printf("usage: %s [options] [disk_image]\n\n"
+           "'disk_image' is a raw hard disk image for IDE hard disk 0\n\n",
+            error_get_progname());
+
 #define QEMU_OPTIONS_GENERATE_HELP
 #include "qemu-options-wrapper.h"
-        ;
-    version();
-    printf("usage: %s [options] [disk_image]\n"
-           "\n"
-           "'disk_image' is a raw hard disk image for IDE hard disk 0\n"
-           "\n"
-           "%s\n"
-           "During emulation, the following keys are useful:\n"
+
+    printf("\nDuring emulation, the following keys are useful:\n"
            "ctrl-alt-f      toggle full screen\n"
            "ctrl-alt-n      switch to virtual console 'n'\n"
            "ctrl-alt        toggle mouse and keyboard grab\n"
            "\n"
-           "When using -nographic, press 'ctrl-a h' to get some help.\n",
-           error_get_progname(),
-           options_help);
+           "When using -nographic, press 'ctrl-a h' to get some help.\n");
+
     exit(exitcode);
 }