Changed wall clock time calculation

Makefile

@@ -40,14 +40,14 @@ mpi_line_async: config utils main_mpi
 		${SRC}/impl/mpi_line_async.c \
 	-o ${BIN}/jacobi_mpi_line_async
 
-main: ${SRC}/main.c
+main: ${SRC}/main/main.c
 	${CC_MPI} -c ${CFLAGS} \
-		${SRC}/main.c \
+		${SRC}/main/main.c \
 	-o ${BUILD}/main.o
 
-main_mpi: ${SRC}/main_mpi.c
+main_mpi: ${SRC}/main/main_mpi.c
 	${CC_MPI} -c ${CFLAGS} \
-		${SRC}/main_mpi.c \
+		${SRC}/main/main_mpi.c \
 	-o ${BUILD}/main_mpi.o
 
 config: ${SRC}/config.c