sha1.c:161:13: warning: ‘SHA1Transform’ reading 64 bytes from a region of size 0

As of commit 248f6f62:

  BUILD   arm-linux-user guest-tests
In function ‘SHA1Update’,
    inlined from ‘SHA1Final’ at tests/tcg/multiarch/sha1.c:201:5:
tests/tcg/multiarch/sha1.c:161:13: warning: ‘SHA1Transform’ reading 64 bytes from a region of size 0 [-Wstringop-overread]
  161 |             SHA1Transform(context->state, &data[i]);
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tests/tcg/multiarch/sha1.c:161:13: note: referencing argument 2 of type ‘const unsigned char[64]’
tests/tcg/multiarch/sha1.c: In function ‘SHA1Final’:
tests/tcg/multiarch/sha1.c:72:6: note: in a call to function ‘SHA1Transform’
   72 | void SHA1Transform(uint32_t state[5], const unsigned char buffer[64])
      |      ^~~~~~~~~~~~~
In function ‘SHA1Update’,
    inlined from ‘SHA1Final’ at tests/tcg/multiarch/sha1.c:204:9:
tests/tcg/multiarch/sha1.c:161:13: warning: ‘SHA1Transform’ reading 64 bytes from a region of size 0 [-Wstringop-overread]
  161 |             SHA1Transform(context->state, &data[i]);
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tests/tcg/multiarch/sha1.c:161:13: note: referencing argument 2 of type ‘const unsigned char[64]’
tests/tcg/multiarch/sha1.c: In function ‘SHA1Final’:
tests/tcg/multiarch/sha1.c:72:6: note: in a call to function ‘SHA1Transform’
   72 | void SHA1Transform(uint32_t state[5], const unsigned char buffer[64])
      |      ^~~~~~~~~~~~~
  RUN     arm-linux-user guest-tests