Fix C90 standard related warning.

This concerns the following:

  ../../../../ext/magic/functions.c: In function ‘override_current_locale’:
  ../../../../ext/magic/functions.c:130:5: warning: ISO C90 forbids mixed
  declarations and code [-Wdeclaration-after-statement]

Signed-off-by: Krzysztof Wilczynski <krzysztof.wilczynski@linux.com>