RE: MinGW compiler warnings in ecpg tests

Dear Peter, Michael,

Sorry for reviving the old thread. While trying to build postgres on msys2 by meson,
I faced the same warning. The OS is Windows 10.

```
$ ninja
[2378/2402] Compiling C object src/interfaces/ecpg/test/sql/sqlda.exe.p/meson-generated_.._sqlda.c.obj
../postgres/src/interfaces/ecpg/test/sql/sqlda.pgc: In function 'dump_sqlda':
../postgres/src/interfaces/ecpg/test/sql/sqlda.pgc:45:33: warning: format '%d' expects argument of type 'int', but
argument3 has type 'long long int' [-Wformat=]
 
   45 |                                 "name sqlda descriptor: '%s' value %I64d\n",
      |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
......
   49 |                                 sqlda->sqlvar[i].sqlname.data, *(long long int *)sqlda->sqlvar[i].sqldata);
      |                                                                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                                                |
      |                                                                long long int
```


Before building, I did below steps:

1. Installed required software listed in [1].
2. ran `meson setup -Dcassert=true -Ddebug=true /path/to/builddir`
3. moved to /path/to/builddir
4. ran `ninja`
5. got above warning

Attached file summarize the result of meson command, which was output at the end of it.
Also, belows show the version of meson/ninja.

```
$ ninja --version
1.11.1
$ meson -v
1.2.3
```

I was quite not sure the windows build, but I could see that gcc compiler was
used here. Does it mean that the compiler might not like the format string "%I64d"?
I modified like below and could be compiled without warnings.

```
--- a/src/interfaces/ecpg/test/sql/sqlda.pgc
+++ b/src/interfaces/ecpg/test/sql/sqlda.pgc
@@ -41,7 +41,7 @@ dump_sqlda(sqlda_t *sqlda)
                        break;
                case ECPGt_long_long:
                        printf(
-#ifdef _WIN32
+#if !defined(__GNUC__)
                                "name sqlda descriptor: '%s' value %I64d\n",
 #else
                                "name sqlda descriptor: '%s' value %lld\n",

```

[1]: https://www.postgresql.org/message-id/9f4f22be-f9f1-b350-bc06-521226b87f7a%40dunslane.net

Best Regards,
Hayato Kuroda
FUJITSU LIMITED