arch/posix: Fix main() renaming trickery
arch/posix: Fix main() renaming trickery

It turns out that SOF is already using a symbol named
"zephyr_app_main()", so this produces a collision.  Pick something
that looks more relevant to "posix", and put an underscore on it (it's
a "system" symbol, after all).

Signed-off-by: Andy Ross <61c3cfd4c0060414f91281a789685c974e47d1ec@google.com>

zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr