misc: fix shadow declarations

misc: fix shadow declarations

sys-utils/zramctl.c: In function 'get_mm_stat':
sys-utils/zramctl.c:276:58: warning: declaration of 'inbytes' shadows a global declaration [-Wshadow]
 static char *get_mm_stat(struct zram *z, size_t idx, int inbytes)
sys-utils/zramctl.c:119:39: note: shadowed declaration is here
 static unsigned int raw, no_headings, inbytes;

libmount/src/tab.c: In function 'mnt_table_get_fs_root':
libmount/src/tab.c:1221:22: warning: declaration of 'fs' shadows a parameter [-Wshadow]
    struct libmnt_fs *fs = mnt_table_find_mountpoint(tb,
libmount/src/tab.c:1197:24: note: shadowed declaration is here
      struct libmnt_fs *fs,

disk-utils/fsck.minix.c: In function 'main':
disk-utils/fsck.minix.c:1364:17: warning: declaration of 'i' shadows a previous local [-Wshadow]
   unsigned long i, free;
disk-utils/fsck.minix.c:1250:6: note: shadowed declaration is here
  int i;

Signed-off-by: Sami Kerola <kerolasa@iki.fi>