maintainer-feedback requested: [Bug 268790] graphics/gimp-app: fix build with clang 15

From: <bugzilla-noreply_at_freebsd.org>
Date: Fri, 06 Jan 2023 20:00:53 UTC
Bugzilla Automation <bugzilla@FreeBSD.org> has asked freebsd-gnome (Nobody)
<gnome@FreeBSD.org> for maintainer-feedback:
Bug 268790: graphics/gimp-app: fix build with clang 15
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=268790



--- Description ---
During an exp-run for llvm 15 (see bug 265425), it turned out that
graphics/gimp-app failed to build with clang 15:

  file-dicom.c:605:26: error: incompatible pointer to integer conversion
returning 'void *' from a function with result type 'gint32' (aka 'int')
[-Wint-conversion]
		    return NULL;
			   ^~~~

This is because the return statement is a function that should return an
integer, not a pointer. Replace it with the error value -1, as used
elsewhere in the function.