undefined references to `sys_rand32_get'

[lorepieri8]

zephyrproject-rtos/zephyr#15565

Describe the bug
I get undefined references to sys_rand32_get'` after building a zephyr app with qemu_cortex_m3 or qemu_x86, while the same setup seems working for nrf52840_pca10056.

To Reproduce
Steps to reproduce the behavior:

1. https://github.com/AnyLedger/anyledger-wallet, commit 8fb0247
2. zephyr build instructions, with zephyr version picked using:

git clone https://github.com/zephyrproject-rtos/zephyr.git
DATE='Nov 7 2018'
git rev-list -1 --before="$DATE" master | xargs -Iz git checkout z

3. cmake -GNinja -DBOARD=qemu_cortex_m3 -DBUILD_XCOMPILE=1 ../
4. ninja
5. See error

Expected behavior
ninja completing the build

Screenshots or console output

libapp.a(compat.c.obj): In function `random32':
/Users/lorenzo/gitHubRepo/nov7zephyr/zephyr/samples/anyledger/anyledger-wallet/build/../zephyr/compat.c:26: undefined reference to `sys_rand32_get'
zephyr/libzephyr.a(coap.c.obj): In function `coap_next_token':
/Users/lorenzo/gitHubRepo/nov7zephyr/zephyr/subsys/net/lib/coap/coap.c:1484: undefined reference to `sys_rand32_get'
/Users/lorenzo/gitHubRepo/nov7zephyr/zephyr/subsys/net/lib/coap/coap.c:1485: undefined reference to `sys_rand32_get'
zephyr/libzephyr.a(slip.c.obj): In function `slip_iface_init':
/Users/lorenzo/gitHubRepo/nov7zephyr/zephyr/drivers/net/slip.c:488: undefined reference to `sys_rand32_get'
zephyr/subsys/net/ip/libsubsys__net__ip.a(net_context.c.obj): In function `find_available_port':
/Users/lorenzo/gitHubRepo/nov7zephyr/zephyr/subsys/net/ip/net_context.c:98: undefined reference to `sys_rand32_get'
zephyr/subsys/net/ip/libsubsys__net__ip.a(net_if.c.obj):/Users/lorenzo/gitHubRepo/nov7zephyr/zephyr/subsys/net/ip/net_if.c:2008: more undefined references to `sys_rand32_get' follow
collect2: error: ld returned 1 exit status
%
ninja: build stopped: subcommand failed.

Environment (please complete the following information):

• OS: MacOS
• ZEPHYR_TOOLCHAIN_VARIANT=gnuarmemb
  -GNUARMEMB_TOOLCHAIN_PATH="~/opt/gcc-arm-none-eabi-7-2018-q2-update/"

Additional context

It works with
cmake -GNinja -DBOARD= nrf52840_pca10056 -DBUILD_XCOMPILE=1 ../
while it doesn't work for
cmake -GNinja -DBOARD= qemu_x86 -DBUILD_XCOMPILE=1 ../