Resolve a warning regarding incompatible pointer types

[japinli]

Hi,
When I build pgtt with PostgreSQL 18beta1:

pgtt.c: In function ‘create_temporary_table_internal’:
pgtt.c:1714:73: warning: passing argument 4 of ‘transformRelOptions’ from incompatible pointer type [-Wincompatible-pointer-types]
 1714 |                                                                         validnsps,
      |                                                                         ^~~~~~~~~
      |                                                                         |
      |                                                                         char **
In file included from pgtt.c:20:
/data/Codes/pg/master/build/pg/include/postgresql/server/access/reloptions.h:223:106: note: expected ‘const char * const*’ but argument is of type ‘char **’
  223 |                                                                  const char *namspace, const char *const validnsps[],
      |

It is because commit 1e35951e in PostgreSQL converts several 'validnsps' static variables into local variables and adds 'const' decorations to the signature of transformRelOptions(). This change results in a build warning regarding incompatible pointer types.

[darold]

Thanks!