Add support for llvm JIT engine

Packages describing “llvm” as local USE flag

Package “llvm” Flag Description
dev-db/postgresql Add support for llvm JIT engine
dev-util/diffoscope Use sys-devel/llvm
net-im/toxic Enables support for LLVM Address Sanitizer
media-gfx/blender Enable features depending on llvm.
media-libs/mesa Enable LLVM backend for Gallium3D.
sci-libs/symengine Build with LLVM
sys-devel/sparse Build the sparse-llvm utility

All packages providing a “llvm” USE flag (6)