Make the panic and UIE handlers turn on the backlight (needed for various colour LCDs that are unreadable without it). UIE is only changed on ARM for now.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22034 a1c6a512-1295-4272-9138-f99709370657

firmware/target/arm/system-arm.c

@@ -23,6 +23,9 @@
 #include <stdio.h>
 #include "lcd.h"
 #include "font.h"
+#ifdef HAVE_BACKLIGHT
+#include "backlight-target.h"
+#endif
 
 static const char* const uiename[] = {
     "Undefined instruction",
@@ -48,6 +51,10 @@ void __attribute__((noreturn)) UIE(unsigned int pc, unsigned int num)
     lcd_puts(0, 1, str);
     lcd_update();
 
+#ifdef HAVE_BACKLIGHT
+    _backlight_on();
+#endif
+
     disable_interrupt(IRQ_FIQ_STATUS);
 
     system_exception_wait(); /* If this returns, try to reboot */