minimal/Makefile: Avoid terminal reset, use BUILD variable.

stty can provide the current terminal settings, so that they can be
stored in a shell variable and restored after running the firmware. This
avoids the complete "blanking" of the terminal, and thus also removes the
need for the sleep call.

The run target now references the firmware file using the BUILD variable
instead of using the hard coded "build/" path.

ports/minimal/Makefile

@@ -103,12 +103,11 @@ deploy: $(BUILD)/firmware.dfu
 
 # Run emulation build on a POSIX system with suitable terminal settings
 run:
-	stty raw opost -echo
-	build/firmware.elf
-	@echo Resetting terminal...
-# This sleep is useful to spot segfaults
-	sleep 1
-	reset
+	@saved_=`stty -g`; \
+	  stty raw opost -echo; \
+	  $(BUILD)/firmware.elf; \
+	  echo "Exit status: $$?"; \
+	  stty $$saved_
 
 test: $(BUILD)/firmware.elf
 	$(Q)/bin/echo -e "print('hello world!', list(x+1 for x in range(10)), end='eol\\\\n')\\r\\n\\x04" | $(BUILD)/firmware.elf | tail -n2 | grep "^hello world! \\[1, 2, 3, 4, 5, 6, 7, 8, 9, 10\\]eol"