When the compiler is configured with --enable-initfini-array,
config/initfini-array.h gets included after config/vxworks.h by tm.h, so
the definitions of TARGET_ASM_CONSTRUTOR/TARGET_ASM_DESTRUCTOR in
vxworks.h get undone in initfini-array.h. Hence, we might as well not
define the vxworks_asm_out_* functions.

From-SVN: r263692