narwhal versus gnu_printf

I noticed that the build logs for buildfarm member narwhal (a mingw
critter) contain an awful lot of occurrences of

../../src/include/utils/elog.h:159: warning: `gnu_printf' is an unrecognized format function type

Evidently, the following hunk in pg_config_manual.h failed to consider
mingw. Is there a simple fix?

/*
* Set the format style used by gcc to check printf type functions. We really
* want the "gnu_printf" style set, which includes what glibc uses, such
* as %m for error strings and %lld for 64 bit long longs. But not all gcc
* compilers are known to support it, so we just use "printf" which all
* gcc versions alive are known to support, except on Windows where
* using "gnu_printf" style makes a dramatic difference. Maybe someday
* we'll have a configure test for this, if we ever discover use of more
* variants to be necessary.
*/
#ifdef WIN32
#define PG_PRINTF_ATTRIBUTE gnu_printf
#else
#define PG_PRINTF_ATTRIBUTE printf
#endif

regards, tom lane