cmake: Fix compilation options for kobject_hash*.c

Rework how the compilation-options for the gperf generated
kobject_hash*.c files are put together to fix problems with SHELL:
and cmake-list separators handling.

zephyr_get_compile_options_for_lang_as_string() returns the set of
options as a cmake generator expression string which is cumbersome to
edit. This caused the command line for the IAR toolchain to have broken
SHELL: entries, and other some command line entries being postfixed by
"gnu".

This also adds CMake compiler properties for no_function_sections and
no_data_sections options

Signed-off-by: Björn Bergman <bjorn.bergman@iar.com>