CMSIS-NN: Link unit test with -specs=nosys.spec for GCC

CMSIS/NN/Tests/UnitTest/CMakeLists.txt

@@ -27,9 +27,12 @@ set_property(GLOBAL PROPERTY cmsis_nn_unit_test_executables)
 # This function should be used instead of add_executable.
 function(add_cmsis_nn_unit_test_executable)
     get_property(tmp GLOBAL PROPERTY cmsis_nn_unit_test_executables)
-    foreach(arg ${ARGV})
-        set(tmp "${tmp} ${arg}")
-        add_executable(${arg})
+    foreach(target ${ARGV})
+        set(tmp "${tmp} ${target}")
+        add_executable(${target})
+        if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+            target_link_options(${target} PRIVATE "--specs=nosys.specs")
+        endif()
     endforeach()
     set_property(GLOBAL PROPERTY cmsis_nn_unit_test_executables "${tmp}")
 endfunction(add_cmsis_nn_unit_test_executable)