message: added -DLLVM_ENABLE_RTTI=1 to centos build instructions in READMD.md
diff: @@ -754,7 +754,8 @@ git clone --depth 1 --single-branch --branch release_40 https://github.com/llvm-
  cd ..
  mkdir build
  cd build
  -cmake -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX=.. -DLLVM_TARGETS_TO_BUILD= -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly -DCMAKE_BUILD_TYPE=Release ../
  +cmake -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX=.. -DLLVM_TARGETS_TO_BUILD= -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly
  +-DLLVM_ENABLE_RTTI=1 -DCMAKE_BUILD_TYPE=Release ../
  make -j$( nproc )
  make install
  ```
  