tests: Add smolnes

To demonstrate the use of SDL-oriented system calls, we can provide
an integrated program that leverages the SDL window system and input
events. Smolnes [1] is an ideal choice due to its minimal footprint
and robust features – it is a Nintendo NES emulator with less than
500 lines of code. Furthermore, we have the option to redistribute
open-source NES ROM files, such as falling-nes [2].

[1] https://github.com/binji/smolnes
[2] https://github.com/xram64/falling-nes

Close #101

Author: jserv

README.md

@@ -292,6 +292,7 @@ In `rv32emu` repository, there are some prebuilt ELF files for testing purpose.
 * `richards.elf` : See [tests/richards.c](tests/richards.c)
 * `rvsim.elf` : See [tests/rvsim.c](tests/rvsim.c)
 * `scimark2.elf` : See [tests/scimark2](tests/scimark2) [RV32MF]
+* `smolnes.elf` : See [tests/smolnes](tests/smolnes.c) [RV32M]
 * `stream.elf` : See [tests/stream](tests/stream.c) [RV32MF]
 
 ## Reference