multimedia/dav1d: disallow Clang LTO on x86

dav1d 0.2.1 - by VideoLAN
Decoded 1/150 frames (0.7%)Process 84877 stopped
* thread DankBSD#1, name = 'dav1d', stop reason = signal SIGBUS: hardware error
    frame #0: 0x000000080028c1f5 libdav1d.so.1`..@26262.end + 101
libdav1d.so.1`..@26262.end:
->  0x80028c1f5 <+101>: vmovdqa %ymm15, (%rsp)
    0x80028c1fa <+106>: callq  0x80028baa0               ; ..@25257.end
    0x80028c1ff <+111>: vpbroadcastd -0x74(%rax), %ymm1
    0x80028c205 <+117>: vpmulhrsw %ymm1, %ymm6, %ymm6
(lldb) reg read rsp
     rsp = 0x00007fffffffc030
(lldb) bt
* thread DankBSD#1, name = 'dav1d', stop reason = signal SIGBUS: hardware error
  * frame #0: 0x000000080028c1f5 libdav1d.so.1`..@26262.end + 101
    frame DankBSD#1: 0x00000008002f605c libdav1d.so.1`read_coef_tree(t=0x0000000800e0f840, bs=BS_16x16, b=0x00007fffffffc630, ytx=2, depth=0, tx_split=0x00007fffffffc644, x_off=0, y_off=0, dst="wwvvvuttuvwxyyxz") at recon_tmpl.c:356:17
    frame DankBSD#2: 0x00000008002fd3cb libdav1d.so.1`dav1d_recon_b_inter_8bpc(t=0x0000000800e0f840, bs=BS_16x16, b=0x00007fffffffc630) at recon_tmpl.c:1510:21
    frame DankBSD#3: 0x00000008002c1180 libdav1d.so.1`decode_b(t=0x0000000800e0f840, bl=BL_16X16, bs=BS_16x16, bp=PARTITION_NONE, intra_edge_flags=0) at decode.c:1855:17
    frame DankBSD#4: 0x00000008002b65d0 libdav1d.so.1`decode_sb(t=0x0000000800e0f840, bl=BL_16X16, node=0x00000008007faf10) at decode.c:2040:17
    frame DankBSD#5: 0x00000008002b68a8 libdav1d.so.1`decode_sb(t=0x0000000800e0f840, bl=BL_32X32, node=0x00000008007f8e20) at decode.c:2084:21
    frame DankBSD#6: 0x00000008002b6924 libdav1d.so.1`decode_sb(t=0x0000000800e0f840, bl=BL_64X64, node=0x00000008007f85a0) at decode.c:2091:21
    frame DankBSD#7: 0x00000008002b6924 libdav1d.so.1`decode_sb(t=0x0000000800e0f840, bl=BL_128X128, node=0x00000008007f8380) at decode.c:2091:21
    frame freebsd#8: 0x00000008002b5fce libdav1d.so.1`dav1d_decode_tile_sbrow(t=0x0000000800e0f840) at decode.c:2542:13
    frame freebsd#9: 0x00000008002cb1ab libdav1d.so.1`dav1d_decode_frame(f=0x0000000800e00000) at decode.c:2916:29
    frame freebsd#10: 0x00000008002cd477 libdav1d.so.1`dav1d_submit_frame(c=0x00000008007f5280) at decode.c:3374:20
    frame freebsd#11: 0x00000008002b1433 libdav1d.so.1`dav1d_parse_obus(c=0x00000008007f5280, in=0x00000008007f52e8, global=0) at obu.c:1490:24
    frame freebsd#12: 0x000000080032f786 libdav1d.so.1`dav1d_get_picture(c=0x00000008007f5280, out=0x00007fffffffe048) at lib.c:359:15
    frame freebsd#13: 0x00000000002035ee dav1d`main(argc=7, argv=0x00007fffffffe250) at dav1d.c:139:20
    frame freebsd#14: 0x000000000020310f dav1d`_start(ap=<unavailable>, cleanup=<unavailable>) at crt1.c:76:7

Reported by:	Mozilla

multimedia/dav1d/Makefile

@@ -29,6 +29,11 @@ CFLAGS_armv6=	-no-integrated-as -B${LOCALBASE}/bin
 CFLAGS_armv7=	-no-integrated-as -B${LOCALBASE}/bin
 LDFLAGS_i386=	-Wl,-z,notext
 
+# https://bugs.llvm.org/show_bug.cgi?id=40635
+CFLAGS+=	${CFLAGS_${CHOSEN_COMPILER_TYPE}_${ARCH}}
+CFLAGS_clang_amd64=	-fno-lto
+CFLAGS_clang_i386=	-fno-lto
+
 OPTIONS_DEFINE=	TEST
 
 TEST_GL_TUPLE=	videolan:dav1d-test-data:3ccdd3df4fb8583d58bcc0101e315b00ec3ae130:testdata/tests/dav1d-test-data