riscv: Fix bootstrap [PR109384]

The following patch unbreaks riscv bootstrap, where it previously failed
on -Werror=format-diag warning promoted to error.

Ok for trunk?

Or shall it say e.g.
"%<-march=%s%>: %<zfinx%> extension conflicts with %<f>"
?
Or say if the current condition is true, do
const char *ext = "zfinx";
if (subset_list->lookup ("zdinx"))
  ext = "zdinx";
else if (subset_list->lookup ("zhinx"))
  ext = "zhinx";
else if (subset_list->lookup ("zhinxmin"))
  ext = "zhinxmin";
and
"%<-march=%s%>: %qs extension conflicts with %<f>", arch, ext
?  Or do similar check for which extension to print against it,
const char *ext = "zfinx";
const char *ext2 = "f";
if (subset_list->lookup ("zdinx"))
  {
    ext = "zdinx";
    if (subset_list->lookup ("d"))
      ext2 = "d";
  }
else if (subset_list->lookup ("zhinx"))
  {
    ext = "zhinx";
    if (subset_list->lookup ("zfh"))
      ext2 = "zfh";
  }
else if (subset_list->lookup ("zhinxmin"))
  {
    ext = "zhinxmin";
    if (subset_list->lookup ("zfhmin"))
      ext2 = "zfhmin";
  }
"%<-march=%s%>: %qs extension conflicts with %qs", arch, ext, ext2
?

2023-04-04  Jakub Jelinek  <jakub@redhat.com>

	PR target/109384
	* common/config/riscv/riscv-common.cc (riscv_subset_list::parse):
	Reword diagnostics about zfinx conflict with f, formatting fixes.

	* gcc.target/riscv/arch-19.c: Expect a different message about zfinx
	vs. f conflict.