Failed to build for LoongArch if vc1 decoder is disabled

[Robin Lee]

Summary of the bug:

Failed to build for loongarch64 if vc1 decoder is disabled.

loongarch64 vc1dsp replies on vc1 decoder symbols when lasx is enabled (the default).

Default FFMpeg in Fedora and Freedesktop SDK must be built with vc1 decoder disabled.

Tested with n6.1.1, n7.1 and master be2cabce327b58a549500bbeb3a342530f2573e9

build error:

/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:57:(.text.unlikely+0x120): undefined reference to `ff_put_vc1_mspel_mc32_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:57:(.text.unlikely+0x124): undefined reference to `ff_put_vc1_mspel_mc32_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:58:(.text.unlikely+0x128): undefined reference to `ff_put_vc1_mspel_mc33_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:58:(.text.unlikely+0x12c): undefined reference to `ff_put_vc1_mspel_mc33_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:58:(.text.unlikely+0x130): undefined reference to `ff_put_vc1_mspel_mc33_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:58:(.text.unlikely+0x134): undefined reference to `ff_put_vc1_mspel_mc33_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:59:(.text.unlikely+0x138): undefined reference to `ff_put_vc1_mspel_mc01_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:59:(.text.unlikely+0x13c): undefined reference to `ff_put_vc1_mspel_mc01_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:60:(.text.unlikely+0x140): undefined reference to `ff_put_vc1_mspel_mc02_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:60:(.text.unlikely+0x144): undefined reference to `ff_put_vc1_mspel_mc02_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:61:(.text.unlikely+0x148): undefined reference to `ff_put_vc1_mspel_mc03_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:61:(.text.unlikely+0x14c): undefined reference to `ff_put_vc1_mspel_mc03_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:62:(.text.unlikely+0x150): undefined reference to `ff_put_vc1_mspel_mc10_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:62:(.text.unlikely+0x154): undefined reference to `ff_put_vc1_mspel_mc10_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:63:(.text.unlikely+0x158): undefined reference to `ff_put_vc1_mspel_mc20_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:63:(.text.unlikely+0x15c): undefined reference to `ff_put_vc1_mspel_mc20_16_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:65:(.text.unlikely+0x19c): undefined reference to `ff_put_no_rnd_vc1_chroma_mc8_lasx'
/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.0/../../../../loongarch64-unknown-linux-gnu/bin/ld: /buildstream-build/libavcodec/loongarch/vc1dsp_init_loongarch.c:65:(.text.unlikely+0x1a0): undefined reference to `ff_put_no_rnd_vc1_chroma_mc8_lasx'

How to reproduce:

0. prepare a loongarch64 buildenv with a recent toolchain
1. ./configure --disable-decoder="vc1"
2. make

[mkver]

Fixed in b515088576bbeb746aa34a222bba76cc01b29e44.