remove unused includes

This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.

src/bootchart/bootchart.c

@@ -33,10 +33,7 @@
 
  ***/
 
-#include <sys/time.h>
-#include <sys/types.h>
 #include <sys/resource.h>
-#include <sys/stat.h>
 #include <stdio.h>
 #include <signal.h>
 #include <stdlib.h>

src/bootchart/bootchart.h

@@ -24,7 +24,6 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-#include <dirent.h>
 #include <stdbool.h>
 #include "list.h"
 

src/bootchart/store.c

@@ -25,8 +25,6 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <limits.h>
-#include <sys/types.h>
-#include <sys/stat.h>
 #include <stdio.h>
 #include <string.h>
 #include <dirent.h>

src/bootchart/svg.c

@@ -23,14 +23,11 @@
  ***/
 
 #include <stdio.h>
-#include <stdarg.h>
-#include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <limits.h>
 #include <unistd.h>
 #include <sys/utsname.h>
-#include <sys/stat.h>
 #include <fcntl.h>
 
 #include "util.h"