malloc test: change stack array to two dimensional array

[maciejbocianski]

Description

Suplement for #5338

• thread stack alignment was removed : the alignment isn't necessary with Ensure Thread stack is 8 byte aligned #5405."
• change stack array to two dimensional array

Status

READY

Migrations

NO

Related PRs

#5338

[maciejbocianski]

CC
@c1728p9

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 439
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/5430/

Triggering tests

/morph test
/morph uvisor-test

[mbed-ci]

Test : FAILURE

Build number : 247
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/5430/247

[0xc0170]

/morph uvisor-test

[0xc0170]

/morph export-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 86
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/5430/

[studavekar]

/morph test

[mbed-ci]

Test : SUCCESS

Build number : 256
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/5430/256

[0xc0170]

/morph uvisor-test

[0xc0170]

@maciejbocianski Please make sure the title describes the pull request in <51 words. Plus the description provided here should be part of the commit (to have it in the git as well)