Remove useless artifacts, revert CFLAGS optimization to native, check if it compiles on musl

.gitlab-ci.yml

@@ -1,15 +1,19 @@
-image: debian:stable-slim
+stages:
+    -build
 
-build:
+debian:
+    image: debian:stable-slim
+    stage: build
     before_script:
         - apt-get -qq update
-        - apt-get -qq install build-essential libsdl2-mixer-dev libsdl2-dev
+        - apt-get -qq install make clang libsdl2-mixer-dev libsdl2-dev
     script:
-        - make
+        - make CC=clang
-    artifacts:
-        name: "generic-x86_64-build"
-        paths:
-            - "bin/chip8"
-            - "resources/buzzer.wav"
-        expire_in: 1 week
 
+alpine:
+    image: alpine:latest
+    stage: build
+    before_script:
+        - apk add make clang sdl2-dev sld2_mixer-dev
+    script:
+        - make CC=clang

Makefile

@@ -1,5 +1,5 @@
 CPPFLAGS = -D_DEFAULT_SOURCE -D_FOTIFY_SOURCE=2
-CFLAGS   = $(CPPFLAGS) -std=c99 -pedantic -Wall -Wextra -mtune=generic -march=x86-64 -O2 -fstack-protector -flto -fPIE -pipe
+CFLAGS   = $(CPPFLAGS) -std=c99 -pedantic -Wall -Wextra -mtune=native -march=native -O2 -fstack-protector -flto -fPIE -pipe
 LDFLAGS  = -Wl,-z,relro,-z,now,-O2,--strip-all -lSDL2 -lSDL2_mixer -flto -pie
 
 default: bin obj bin/chip8