maint: fix shadow declaration

maint: fix shadow declaration

This change fixes all shadow declarations.  The worth while to mention
fix is with libfdisk sun geometry.  It comes from bitops.h cpu_to_be16
macro that further expands from include/bits/byteswap.h that has the
shadowing.

libfdisk/src/sun.c:961:173: warning: declaration of '__v' shadows a previous local [-Wshadow]
libfdisk/src/sun.c:961:69: warning: shadowed declaration is here [-Wshadow]
libfdisk/src/sun.c:961:178: warning: declaration of '__x' shadows a previous local [-Wshadow]
libfdisk/src/sun.c:961:74: warning: shadowed declaration is here [-Wshadow]

That could have caused earlier some unexpected results.

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