InnoDB: Replace for loops with memset() where possible.

innobase/btr/btr0cur.c:
  Replace for loop with memset()
innobase/buf/buf0buf.c:
  buf_print(): Remove for loop for initializing counts[].
  Similar to index_ids[], the elements of this array will
  be initialized when they are allocated, i.e., counts[n_found++] = 1.
innobase/os/os0file.c:
  Replace for loop with memset()
innobase/page/page0page.c:
  Replace for loop with memset()
innobase/trx/trx0rec.c:
  Replace for loop with memset()

innobase/btr/btr0cur.c

@@ -2847,9 +2847,7 @@ btr_estimate_number_of_different_key_vals(
 
 	n_diff = mem_alloc((n_cols + 1) * sizeof(ib_longlong));
 
-	for (j = 0; j <= n_cols; j++) {
-		n_diff[j] = 0;
-	}
+	memset(n_diff, 0, (n_cols + 1) * sizeof(ib_longlong));
 
 	/* We sample some pages in the index to get an estimate */
 	

innobase/buf/buf0buf.c

@@ -2101,10 +2101,6 @@ buf_print(void)
 	
 	n_found = 0;
 
-	for (i = 0 ; i < size; i++) {
-		counts[i] = 0;
-	}
-
 	for (i = 0; i < size; i++) {
 		frame = buf_pool_get_nth_block(buf_pool, i)->frame;
 

innobase/os/os0file.c

@@ -1672,7 +1672,6 @@ os_file_set_size(
 	ibool		ret;
 	byte*   	buf;
 	byte*   	buf2;
-	ulint   	i;
 
 	ut_a(size == (size & 0xFFFFFFFF));
 
@@ -1685,9 +1684,7 @@ os_file_set_size(
 	buf = ut_align(buf2, UNIV_PAGE_SIZE);
 
 	/* Write buffer full of zeros */
-	for (i = 0; i < UNIV_PAGE_SIZE * 512; i++) {
-	        buf[i] = '\0';
-	}
+	memset(buf, 0, UNIV_PAGE_SIZE * 512);
 
 	offset = 0;
 	low = (ib_longlong)size + (((ib_longlong)size_high) << 32);

innobase/page/page0page.c

@@ -1755,9 +1755,7 @@ page_validate(
 	records in the page record heap do not overlap */
 
 	buf = mem_heap_alloc(heap, UNIV_PAGE_SIZE);
-	for (i = 0; i < UNIV_PAGE_SIZE; i++) {
-		buf[i] = 0;
-	}
+	memset(buf, 0, UNIV_PAGE_SIZE);
 
 	/* Check first that the record heap and the directory do not
 	overlap. */

innobase/trx/trx0rec.c

@@ -941,13 +941,11 @@ trx_undo_erase_page_end(
 	mtr_t*	mtr)		/* in: mtr */
 {
 	ulint	first_free;
-	ulint	i;
 
 	first_free = mach_read_from_2(undo_page + TRX_UNDO_PAGE_HDR
 							+ TRX_UNDO_PAGE_FREE);
-	for (i = first_free; i < UNIV_PAGE_SIZE - FIL_PAGE_DATA_END; i++) {
-		undo_page[i] = 0xFF;
-	}
+	memset(undo_page + first_free, 0xff,
+		(UNIV_PAGE_SIZE - FIL_PAGE_DATA_END) - first_free);
 
 	mlog_write_initial_log_record(undo_page, MLOG_UNDO_ERASE_END, mtr);
 }