multimedia/libdv: add -znotext to LDFLAGS on i386, for lld

Example error:

/usr/bin/ld: error: can't create dynamic relocation R_386_32 against

symbol: dv_vlc_class_index_mask in readonly segment; recompile
object files with -fPIC

defined in .libs/vlc.o
referenced by .libs/vlc_x86.o:(.text+0xF)

This port links some non-PIC code, which fails with lld as it defaults
to disallowing relocations against read-only segments. For i386 we can
just add -znotext unconditionally: for GNU BFD ld it just affirms BFD's
existing default.

PR: 214864
Approved by: bapt
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17220