security/john: fix build on powerpc64*

cc -DAC_BUILT -maltivec -mvsx -mpower8-vector -DJOHN_ALTIVEC -c -m64 -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -I/usr/local/include -I/usr/include -DARCH_LITTLE_ENDIAN=1 -DJOHN_SYSTEMWIDE -DJOHN_SYSTEMWIDE_EXEC='"/usr/local/bin"' -DJOHN_SYSTEMWIDE_HOME='"/usr/local/share/john"' -DJOHN_SYSTEMWIDE=1 -Wall -Wno-tautological-constant-out-of-range-compare -fno-omit-frame-pointer -Wno-deprecated-declarations -Wformat-extra-args -Qunused-arguments -std=gnu89 -Wdate-time -D__BSD_VISIBLE -I/usr/include -fopenmp -D_THREAD_SAFE -pthread -I/usr/local/include -DCL_SILENCE_DEPRECATION -finline-functions -fno-strict-aliasing -maltivec DES_bs_b.c
In file included from DES_bs_b.c:620:
./sboxes-s.c:59:2: warning: implicit declaration of function 'vec_sel' [-Wimplicit-function-declaration]

vsel(x0F0F3333, a3, a2, a5);
^

DES_bs_b.c:117:10: note: expanded from macro 'vsel'

(dst) = vec_sel((a), (b), (vector bool int)(c))
        ^

In file included from DES_bs_b.c:620:
./sboxes-s.c:59:2: error: assigning to 'vtype' (vector of 4 'int' values) from incompatible type 'int'

vsel(x0F0F3333, a3, a2, a5);
^~~~~~~~~~~~~~~~~~~~~~~~~~~

DES_bs_b.c:117:8: note: expanded from macro 'vsel'

(dst) = vec_sel((a), (b), (vector bool int)(c))
      ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~