cpukit/libdebugger: Avoid cascade for interrupts

This updates behavior of libdebugger to handle debug exceptions in
interrupt context by temporarily removing a software breakpoint,
stepping, and then resuming afterward.

cpukit/libdebugger/rtems-debugger-target.h

@@ -221,6 +221,11 @@ extern int rtems_debugger_target_swbreak_insert(void);
  */
 extern int rtems_debugger_target_swbreak_remove(void);
 
+/**
+ * Determine whether a software breakpoint is configured for the given address.
+ */
+extern bool rtems_debugger_target_swbreak_is_configured( uintptr_t addr );
+
 /**
  * Insert hardware breakpoints into the hardware.
  */