Use c11 on POSIX platforms and be pedantic about it

build_posix.sh

@@ -3,7 +3,7 @@
 set -xe
 
 CC=cc
-CFLAGS="-Wall -Wextra -ggdb -I./include/"
+CFLAGS="-Wall -Wextra -std=c11 -pedantic -ggdb -I./include/"
 LIBS="-lglfw -lGL -lm"
 
 $CC $CFLAGS -o main main.c $LIBS