In commit 2e47f35be5dc libllvm, libclang and liblldb were converted into
private shared libraries. This allowed clang, lld, lldb, and other llvm
tools to be linked against these shared libraries, which makes them
smaller and avoids duplication.
However, this also comes at the cost of some performance, since the
dynamic libraries are quite large, and contain lots of long symbols
(mangled C++ identifiers).
Add a WITH_LLVM_STATIC build knob that can be used to go back to the
previous behavior: libllvm, libclang and liblldb are built as internal
static libraries, i.e. only available during buildworld, and fully
linked into the various executables such as clang, lld, etc.
PR: 287447
MFC after: 1 week