has_icu failing because of false icu path when loading icu libraries

I am trying to compile boost 1.70 with ICU support. For this I have these to commands in a shell script:

```
./bootstrap.sh --with-icu="$ICU_DIR}" \
--with-libraries=atomic,chrono,container,context,contract,coroutine,date_time,exception,fiber,filesystem,graph,graph_parallel,iostreams,locale,log,math,mpi,program_options,random,regex,serialization,stacktrace,system,test,thread,type_erasure,timer,wave

./b2 --layout=tagged \
cxxstd=17 \
toolset=gcc \
variant=release \
threading=multi \
link=shared \
address-model=64 \
-sZLIB_SOURCE=$ZLIB_DIR \
-q -sBZIP2_SOURCE=$BZIP2_DIR \
-sICU_PATH="${ICU_DIR}" \
include="${ICU_DIR}/include" \
-sICU_LINK="-L${ICU_DIR}/lib64 -licuuc -licudata -licui18n"
```

The variable `ICU_DIR` is pointing to a directory, where my ICU stuff is there, i.e. in `ICU_DIR/include` are the header files and in `ICU_DIR/lib64` are the libraries, e.g. `libicudata.so.61`, `libicui18n.so.61`. So I have this directory structure:

```
ICU_DIR
ICU_DIR/bin
ICU_DIR/bin64
ICU_DIR/include
ICU_DIR/lib
ICU_DIR/lib64
```

The directories `bin` and `lib` are for 32 bit, `bin64` and `lib64` respectively for 64 bit versions of the library.

During compilation I see in the logs this:

> - has_icu builds : no
> ...
> - icu : yes

Then I checked the files `boost_1_70_0/bin.v2/config.log`. There I can find this error

> bin.v2/libs/regex/build/gcc-8.3.1/debug/cxxstd-17-iso/threading-multi/visibility-hidden/has_icu: error while loading shared libraries: libicudata.so.61: cannot open shared object file: No such file or directory
> LD_LIBRARY_PATH="${ICU_DIR}/bin:/opt/rh/devtoolset-8/root/usr/bin:/opt/rh/devtoolset-8/root/usr/lib:/opt/rh/devtoolset-8/root/usr/lib32:/opt/rh/devtoolset-8/root/usr/lib64:$LD_LIBRARY_PATH

Then, I thought of changing my compiling command to something like this:

`LD_LIBRARY_PATH=$LD_LIBRARY_PATH:${ICU_DIR}/lib64 ./b2 --layout=tagged ...`

but then I get this error message during build

```
error: Name clash for '

libboost_atomic-mt-x64.so.1.70.0'
error:
error: Tried to build the target twice, with property sets having
error: these incompatible properties:
error:
error: - none
error: - ${ICU_DIR}/bin -L${ICU_DIR}/lib64 -licudata -licui18n -licuuc
error:
error: Please make sure to have consistent requirements for these
error: properties everywhere in your project, especially for install
error: targets.
```

This `dll-path` is false here. In my case, it should look to this `lib64` directory not to the `bin` directory, but I don't know how to adjsut that when starting `b2`.