Enable address and undefined behavior sanitizers

scripts/build.sh

@@ -3,6 +3,7 @@ cd "$(git rev-parse --show-toplevel)"
 CFLAGS="$CFLAGS -std=c11 -pedantic -Wall -Wextra"
 CFLAGS="$CFLAGS -O0 -ggdb"
 CFLAGS="$CFLAGS -Ilib/include"
+CFLAGS="$CFLAGS -fsanitize=address,undefined"
 
 mkdir -p build