llvm: Build LLVM with run-time type information

> -D=LLVM_ENABLE_RTTI=ON: Used to build LLVM with run-time type
> information. This is required for building Mesa-19.0.4.

Required by Mesa 3D Nouveau driver.

    Dependency LLVM (modules: amdgpu, asmparser, bitreader, bitwriter, engine, ipo, mcdisassembler, mcjit, native) found: YES 7.0.1

    meson.build:1277:6: ERROR: Problem encountered: The Nouveau driver requires rtti. You either need to turn off nouveau or use an LLVM built with LLVM_ENABLE_RTTI.

[1]: http://www.linuxfromscratch.org/blfs/view/svn/general/llvm.html

llvm.be0

@@ -58,6 +58,7 @@ mee_configure() {
       -DCMAKE_BUILD_TYPE=Release \
       -DLLVM_BUILD_LLVM_DYLIB=ON \
       -DLLVM_LINK_LLVM_DYLIB=ON \
+      -DLLVM_ENABLE_RTTI=ON \
       -DLLVM_TARGETS_TO_BUILD="X86;AMDGPU;BPF" \
       -DLLVM_INSTALL_UTILS=ON
 }