[coreutils] Support freebsd style bs=1m for 'dd'

[Дмитрий Ильин]

Greetings coreutils developers!

First of all i would like to thank you for the great work you are doing for 
free software community.

Recently i noticed that coreutils 'dd' doesn't support bs=1m as freebsd user 
usually type.
For example:
Freebsd:
dd if=/dev/ad0 of=/dev/null bs=1m
Linux:
dd if=/dev/sda of=/dev/null bs=1M

If i try bs=1m with linux i get dd: invalid number `1m'

I looked into lib/xstrtol.c and found

        case 'G': /* giga or gibi */
        case 'g': /* 'g' is undocumented; for compatibility only */
          overflow = bkm_scale_by_power (&tmp, base, 3);
          break;

        case 'k': /* kilo */
        case 'K': /* kibi */
          overflow = bkm_scale_by_power (&tmp, base, 1);
          break;

        case 'M': /* mega or mebi */
        case 'm': /* 'm' is undocumented; for compatibility only */
          overflow = bkm_scale_by_power (&tmp, base, 2);
          break;

Looks like 'k' and 'K' for kilo, 'g' and 'G' for giga, 'm' and 'M' for mega are 
all supported.

Then i looked into src/dd.c

enum strtol_error e = xstrtoumax (str, &suffix, 10, &n, "bcEGkKMPTwYZ0");

'm' letter is missing.

So let's add 'm' letter too. It will be very useful for people who use both 
freebsd and linux so then will not have to remember should they type 'm' or 
'M'. Freebsd users always use 'm'.

--- a/src/dd.c  2010-04-20 23:52:04.000000000 +0400
+++ b/src/dd.c  2010-09-11 15:45:37.721873080 +0400
@@ -968,7 +968,7 @@
 {
   uintmax_t n;
   char *suffix;
-  enum strtol_error e = xstrtoumax (str, &suffix, 10, &n, "bcEGkKMPTwYZ0");
+  enum strtol_error e = xstrtoumax (str, &suffix, 10, &n, "bcEGkKmMPTwYZ0");
 
   if (e == LONGINT_INVALID_SUFFIX_CHAR && *suffix == 'x')
     {