pdf2djvu: drop clang builds

it no longer builds with libc++ 19 and upstream is no longer maintained:
jwilk-archive/pdf2djvu#157

context: #22340

Author: lazka

mingw-w64-pdf2djvu/PKGBUILD

@@ -7,7 +7,7 @@ pkgver=0.9.19
 pkgrel=11
 pkgdesc="Creates DjVu files from PDF files (mingw-w64)"
 arch=('any')
-mingw_arch=('mingw64' 'ucrt64' 'clang64' 'clangarm64')
+mingw_arch=('mingw64' 'ucrt64')
 url="https://jwilk.net/software/pdf2djvu"
 license=('spdx:GPL-2.0-or-later')
 depends=("${MINGW_PACKAGE_PREFIX}-gcc-libs"