tree-wide: convert open calls to remove spaces to skip_spaces() lib function

Makes use of skip_spaces() defined in lib/string.c for removing leading
spaces from strings all over the tree.

It decreases lib.a code size by 47 bytes and reuses the function tree-wide:
   text    data     bss     dec     hex filename
  64688     584     592   65864   10148 (TOTALS-BEFORE)
  64641     584     592   65817   10119 (TOTALS-AFTER)

Also, while at it, if we see (*str && isspace(*str)), we can be sure to
remove the first condition (*str) as the second one (isspace(*str)) also
evaluates to 0 whenever *str == 0, making it redundant. In other words,
"a char equals zero is never a space".

Julia Lawall tried the semantic patch (http://coccinelle.lip6.fr) below,
and found occurrences of this pattern on 3 more files:
    drivers/leds/led-class.c
    drivers/leds/ledtrig-timer.c
    drivers/video/output.c

@@
expression str;
@@

( // ignore skip_spaces cases
while (*str &&  isspace(*str)) { \(str++;\|++str;\) }
|
- *str &&
isspace(*str)
)

Signed-off-by: André Goddard Rosa <[email protected]>
Cc: Julia Lawall <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Richard Purdie <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Kyle McMartin <[email protected]>
Cc: Henrique de Moraes Holschuh <[email protected]>
Cc: David Howells <[email protected]>
Cc: <[email protected]>
Cc: Samuel Ortiz <[email protected]>
Cc: Patrick McHardy <[email protected]>
Cc: Takashi Iwai <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

drivers/md/dm-table.c

@@ -12,6 +12,7 @@
 #include <linux/blkdev.h>
 #include <linux/namei.h>
 #include <linux/ctype.h>
+#include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/mutex.h>
@@ -600,11 +601,8 @@ int dm_split_args(int *argc, char ***argvp, char *input)
 		return -ENOMEM;
 
 	while (1) {
-		start = end;
-
 		/* Skip whitespace */
-		while (*start && isspace(*start))
-			start++;
+		start = skip_spaces(end);
 
 		if (!*start)
 			break;	/* success, we hit the end */

drivers/md/md.c

@@ -39,6 +39,7 @@
 #include <linux/buffer_head.h> /* for invalidate_bdev */
 #include <linux/poll.h>
 #include <linux/ctype.h>
+#include <linux/string.h>
 #include <linux/hdreg.h>
 #include <linux/proc_fs.h>
 #include <linux/random.h>
@@ -3439,8 +3440,7 @@ bitmap_store(mddev_t *mddev, const char *buf, size_t len)
 		}
 		if (*end && !isspace(*end)) break;
 		bitmap_dirty_bits(mddev->bitmap, chunk, end_chunk);
-		buf = end;
-		while (isspace(*buf)) buf++;
+		buf = skip_spaces(end);
 	}
 	bitmap_unplug(mddev->bitmap); /* flush the bits to disk */
 out: