Add a no-op breakpoint_me for easy gdb'ing.

flow/Error.cpp

@@ -117,3 +117,7 @@ void ErrorCodeTable::addCode(int code, const char *name, const char *description
 bool isAssertDisabled(int line) {
 	return FLOW_KNOBS && (FLOW_KNOBS->DISABLE_ASSERTS == -1 || FLOW_KNOBS->DISABLE_ASSERTS == line);
 }
+
+void breakpoint_me() {
+	return;
+}

flow/Error.h

@@ -98,6 +98,8 @@ extern bool isAssertDisabled( int line );
 	catch(Error &e) { criticalError(FDB_EXIT_ABORT, "AbortOnError", e.what()); } \
 	catch(...) { criticalError(FDB_EXIT_ABORT, "AbortOnError", "Aborted due to unknown error"); }
 
+EXTERNC void breakpoint_me();
+
 #ifdef FDB_CLEAN_BUILD
 #  define NOT_IN_CLEAN BOOST_STATIC_ASSERT_MSG(0, "This code can not be enabled in a clean build.");
 #else