target/s390x/arch_dump: Fix warning for the name field in the PT_NOTE section

target/s390x/arch_dump: Fix warning for the name field in the PT_NOTE section

There is a compiler warning with GCC 9.3 when compiling with
the -fsanitize=thread compiler flag:

 In function 'strncpy',
    inlined from 's390x_write_elf64_notes' at ../target/s390x/arch_dump.c:219:9:
 /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error:
  '__builtin_strncpy' specified bound 8 equals destination size
  [-Werror=stringop-truncation]

Since the name should always be NUL-terminated, let's use g_strlcpy() to
silence this warning. And while we're at it, also add an assert() to make
sure that the provided names always fit the size field (which is fine for
the current callers, the function is called once with "CORE" and once with
"LINUX" as a name).

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <20210205093921.848260-1-thuth@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>