pipeline_exec() complete

+ TODO : simple_cmd_builtin()
+ libft small update

Makefile

@@ -5,9 +5,11 @@ CC = clang
 CFLAGS = -Wall -Wextra $(INCLUDES) -g # add -Werror, del -g
 
 VPATH  = $(DIR_SRCS)
-DIR_SRCS =	srcs srcs/builtins srcs/lexing \
+DIR_SRCS =	srcs srcs/builtins \
+			srcs/lexing \
 			srcs/parsing srcs/parsing/valid_syntax \
-			srcs/parsing/expansions srcs/parsing/redirections
+			srcs/parsing/expansions srcs/parsing/redirections \
+			srcs/exec
 
 INCLUDES = -I$(HEADERS_D) -I$(LIBFT_D)