[gimp/wip/Jehan/meson-windows-official] build: do not build file-mng for 32-bit Windows.

[Jehan <jehanp src gnome org>]

commit e728cc911c467ece14afde4af9bcf2640b1c7d25
Author: Jehan <jehan girinstud io>
Date:   Thu Mar 31 00:14:51 2022 +0200

    build: do not build file-mng for 32-bit Windows.
    
    We didn't need to do this on the autotools build, simply because the
    configure step is much more elaborated there, and was checking for the
    header file as well as well as a working mng_create() API. But since
    libmng was broken, the test failed, so we didn't need to disable it.
    
    By the way, we should check when the `.pc` file was added, because if it
    was after the required version, then the meson test is very wrong. It
    should not have been different from the autotools file.

 build/windows/gitlab-ci/build-gimp-msys2.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/build/windows/gitlab-ci/build-gimp-msys2.sh b/build/windows/gitlab-ci/build-gimp-msys2.sh
index 5f5ec18b57..38d320cb31 100644
--- a/build/windows/gitlab-ci/build-gimp-msys2.sh
+++ b/build/windows/gitlab-ci/build-gimp-msys2.sh
@@ -6,7 +6,8 @@ if [[ "$MSYSTEM" == "MINGW32" ]]; then
     export ARTIFACTS_SUFFIX="-w32"
     export MSYS2_ARCH="i686"
     export MSYS2_PREFIX="/c/msys64/mingw32"
-    export GIMP_OPTIONS="-Dvala-plugins=disabled"
+    # 32-bit libmng MSYS2 package is broken: https://github.com/msys2/MINGW-packages/issues/11136
+    export GIMP_OPTIONS="-Dvala-plugins=disabled -Dmng=false"
 else
     export ARTIFACTS_SUFFIX="-w64"
     export MSYS2_ARCH="x86_64"