Make umf_utils an interface library

So that users of umf pools (which are static libraries)
do not have to link with umf_utils themselves.

It's not possible to link static libraries to other
static libraries.

Author: igchor

test/CMakeLists.txt

@@ -210,6 +210,7 @@ add_umf_test(
     NAME base_alloc
     SRCS ${BA_SOURCES_FOR_TEST} test_base_alloc.cpp
     LIBS ${UMF_UTILS_FOR_TEST})
+    
 add_umf_test(
     NAME base_alloc_linear
     SRCS ${BA_SOURCES_FOR_TEST} test_base_alloc_linear.cpp