gcc warning messages for 0.5.0

[mkgrgis]

There is clean gcc (10.2.1 20210110) output for firebird_fdw, but warnings for libfq.

src/libfq.c: In function ‘_FQexecParams’:
src/libfq.c:1904:36: warning: initialization of ‘isc_blob_handle’ {aka ‘unsigned int’} from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
 1904 |      isc_blob_handle blob_handle = NULL;
      |                                    ^~~~
src/libfq.c: In function ‘_FQformatDatum’:
src/libfq.c:3483:43: warning: initialization of ‘isc_blob_handle’ {aka ‘unsigned int’} from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
 3483 |             isc_blob_handle blob_handle = NULL;
      |                                           ^~~~

[ibarwick]

Ah yes, thanks for the reminder, that was probably a late-night fix from back when I was puzzling through the Firebird BLOB API. Fixed.