tests/kernel/mem_protect/userspace: test that _k_neg_eagain is in rodata
tests/kernel/mem_protect/userspace: test that _k_neg_eagain is in rodata

Explicitly test that _k_neg_eagain is in rodata.

Signed-off-by: Stephen Smalley <d6e1285e1c84d3d5885c2124fdacc780e9fc0a94@tycho.nsa.gov>

nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,kraj/zephyr,galak/zephyr,kraj/zephyr,nashif/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,aceofall/zephyr-iotos,zephyriot/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,zephyriot/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,mbolivar/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,Vudentz/zephyr,Vudentz/zephyr,aceofall/zephyr-iotos,punitvara/zephyr,zephyriot/zephyr,Vudentz/zephyr,mbolivar/zephyr,nashif/zephyr,mbolivar/zephyr,nashif/zephyr,Vudentz/zephyr,mbolivar/zephyr,punitvara/zephyr,ldts/zephyr,kraj/zephyr,finikorg/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,finikorg/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,kraj/zephyr,aceofall/zephyr-iotos,galak/zephyr,galak/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,aceofall/zephyr-iotos,zephyriot/zephyr,ldts/zephyr,punitvara/zephyr,Vudentz/zephyr,mbolivar/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,explora26/zephyr,explora26/zephyr,explora26/zephyr,zephyriot/zephyr,galak/zephyr,kraj/zephyr