build: Add missing includes to libutil CMake target. (#4306)

This is the continuation of [4305
](#4305
extra step to Makefile config target to force CMake to rescan).
The error occurs when configuring with `make
OpenImageIO_BUILD_MISSING_DEPS=all` option which fails the build as
`libuitil` does not have `./dep/dist/include` on the path.
The original solution was to rerun cmake and let it rescan paths. This
step was only required to run once - after the initial CMake
configuration step. This kind off worked but I'm still unsure why. So
instead of that we can just add the missing location to CMakeLists.

Signed-off-by: kuba <kuba456@gmail.com>

src/libutil/CMakeLists.txt

@@ -47,6 +47,7 @@ function (setup_oiio_util_library targetname)
 
     target_include_directories (${targetname}
             PUBLIC
+                $<BUILD_INTERFACE:${OpenImageIO_LOCAL_DEPS_ROOT}/include>
                 $<INSTALL_INTERFACE:include>
             PRIVATE
                 ${ROBINMAP_INCLUDES}