change gdb port to 26000

Makefile

@@ -160,7 +160,7 @@ clean:
 	$(UPROGS)
 
 # try to generate a unique GDB port
-GDBPORT = $(shell expr `id -u` % 5000 + 25000)
+GDBPORT = 26000
 # QEMU's gdb stub command line changed in 0.11
 QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
 	then echo "-gdb tcp::$(GDBPORT)"; \