PR #12225 broke ARMCC for LPC1768 - heap symbol not defined

[0xc0170]

Description of defect

This PR most probably broke the LPC1768 build: https://github.com/ARMmbed/mbed-os/pull/12225/files#diff-69c41b8becb0d25b48320173a11f0b82R113 (from PR #12225)

It changes the mbed sdk boot code file. This is the error:

Error: L6218E: Undefined symbol Image$$ARM_LIB_HEAP$$ZI$$Length (referred from BUILD/LPC1768/ARM-DEVELOP/mbed-os/platform/source/mbed_sdk_boot.o).

The tests failed also in the PR (CI failed to report red, it passed but if you check artifacts, the error is there).

@ARMmbed/mbed-os-core Please review

Target(s) affected by this defect ?

LPC1768

Toolchain(s) (name and version) displaying this defect ?

ARM

What version of Mbed-os are you using (tag or sha) ?

mbed-os-99.99.99

What version(s) of tools are you using. List all that apply (E.g. mbed-cli)

not applicable

How is this defect reproduced ?

Build blinky baremetal (mbed-os-example-blinky-baremetal) example with Mbed OS master

[0xc0170]

ARCH PRO as well. Based on the same MCU.

There are more errors in the build however not related to the PR itself, I'll create new issues for these. But please verify that only ARMCC and only LPC176x based were affected.

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOTRIAGE-2533