[SeaBIOS] GCC 10: tcgbios.c:290:30: warning: array subscript '(<unknown>) + 4294967295' is outside the bounds of an interior zero-length array 'struct TCG_EfiSpecIdEventAlgorithmSize[0]' [-Wzero-length-bounds]

[Paul Menzel]

Dear SeaBIOS folks,

Building SeaBIOS master with GCC 10 from Debian Sid/unstable, the
compiler shows the warning below.

```
$ make CC=gcc-10 V=1
[…]
  Compile checking out/src/tcgbios.o
gcc-10 -Iout/ -Isrc -Os -MD -g -Wall -Wno-strict-aliasing -Wold-style-definition -Wtype-limits -m32 -march=i386 -mregparm=3 -mpreferred-stack-boundary=2 -minline-all-stringops -fomit-frame-pointer -freg-struct-return -ffreestanding -fno-delete-null-pointer-checks -ffunction-sections -fdata-sections -fno-common -fno-merge-constants  -fno-pie -fno-stack-protector  -fstack-check=no -Wno-address-of-packed-member -DMODE16=0 -DMODESEGMENT=0 -c src/tcgbios.c -o out/src/tcgbios.o
src/tcgbios.c: In function 'tpm20_write_EfiSpecIdEventStruct':
src/tcgbios.c:290:30: warning: array subscript '(<unknown>) + 4294967295' is outside the bounds of an interior zero-length array 'struct TCG_EfiSpecIdEventAlgorithmSize[0]' [-Wzero-length-bounds]
  290 |         event.hdr.digestSizes[count].algorithmId = be16_to_cpu(sel->hashAlg);
      |         ~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In file included from src/tcgbios.c:22:
src/std/tcg.h:527:7: note: while referencing 'digestSizes'
  527 |     } digestSizes[0];
      |       ^~~~~~~~~~~
src/tcgbios.c:291:30: warning: array subscript '(<unknown>) + 4294967295' is outside the bounds of an interior zero-length array 'struct TCG_EfiSpecIdEventAlgorithmSize[0]' [-Wzero-length-bounds]
  291 |         event.hdr.digestSizes[count].digestSize = hsize;
      |         ~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In file included from src/tcgbios.c:22:
src/std/tcg.h:527:7: note: while referencing 'digestSizes'
  527 |     } digestSizes[0];
      |       ^~~~~~~~~~~
[…]
```

Kind regards,

Paul