Command line support for altering the log file location

Add command line support for logging to a location other than /tmp/qemu.log.

With logging enabled (command line option -d), the log is written to
the hard-coded path /tmp/qemu.log. This patch adds support for writing
the log to a different location by passing the -D option.

Signed-off-by: Matthew Fernandez <matthew.fernandez@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index f2ef9a1..37e54ee 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2007,6 +2007,15 @@
 Output log in /tmp/qemu.log
 ETEXI
 
+DEF("D", HAS_ARG, QEMU_OPTION_D, \
+    "-D logfile      output log to logfile (instead of the default /tmp/qemu.log)\n",
+    QEMU_ARCH_ALL)
+STEXI
+@item -D
+@findex -D
+Output log in logfile instead of /tmp/qemu.log
+ETEXI
+
 DEF("hdachs", HAS_ARG, QEMU_OPTION_hdachs, \
     "-hdachs c,h,s[,t]\n" \
     "                force hard disk 0 physical geometry and the optional BIOS\n" \