[Bug rtl-optimization/89490] char array constant put in string merge section

[amodra at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89490

--- Comment #1 from Alan Modra <amodra at gmail dot com> ---
Reduced C testcase, compile at -O1.

static const unsigned char utf8_bom[3] = { 0xEF, 0xBB, 0xBF };

void
plonk (unsigned char *p)
{
  __builtin_memcpy (p, utf8_bom, 3);
}