sci-ml/caffe2: fix llvm build

Closes: https://bugs.gentoo.org/953366
Signed-off-by: Alfredo Tupone <tupone@gentoo.org>

sci-ml/caffe2/caffe2-2.7.0-r2.ebuild

@@ -139,10 +139,13 @@ PATCHES=(
 	"${FILESDIR}"/${PN}-2.6.0-rocm-fix-std-cpp17.patch
 	"${FILESDIR}"/${P}-cmake.patch
 	"${FILESDIR}"/${P}-glog-0.7.1.patch
+	"${FILESDIR}"/${P}-llvm.patch
 )
 
 src_prepare() {
-	use flash && mv "${WORKDIR}"/${FLASH_P}/* third_party/${FLASH_PN}/ || die
+	if use flash; then
+		mv "${WORKDIR}"/${FLASH_P}/* third_party/${FLASH_PN}/ || die
+	fi
 	filter-lto #bug 862672
 
 	# Unbundle fmt

sci-ml/caffe2/files/caffe2-2.7.0-llvm.patch

@@ -0,0 +1,15 @@
+--- a/c10/util/strong_type.h	2025-06-29 10:28:19.365533325 +0200
++++ b/c10/util/strong_type.h	2025-06-29 10:28:40.944598046 +0200
+@@ -1604,12 +1604,6 @@
+     return hash<T>::operator()(value_of(tt));
+   }
+ };
+-template <typename T, typename Tag, typename ... M>
+-struct is_arithmetic<::strong::type<T, Tag, M...>>
+-  : is_base_of<::strong::arithmetic::modifier<::strong::type<T, Tag, M...>>,
+-               ::strong::type<T, Tag, M...>>
+-{
+-};
+ 
+ #if STRONG_HAS_STD_FORMAT
+ template<typename T, typename Tag, typename... M, typename Char>