Tools: Fix Python3 + firmware header traeback

[theotherjimmy]

Description

Traceback:

Merging Regions
  Filling region bootloader with mbed-cloud-client-example/mbed-os/features/FEATURE_BOOTLOADER/targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/TARGET_FRDM/mbed-bootloader-k64f-block_device-sotp-v3_4_0.bin
  Padding region bootloader with 0x9a4 bytes
Traceback (most recent call last):
  File "mbed-cloud-client-example/mbed-os/tools/make.py", line 293, in <module>
    ignore=options.ignore
  File "mbed-cloud-client-example/mbed-os/tools/build_api.py", line 548, in build_project
    merge_region_list(region_list, res, notify)
  File "mbed-cloud-client-example/mbed-os/tools/build_api.py", line 423, in merge_region_list
    _fill_header(region_list, region).tofile(header_filename, format='hex')
  File "mbed-cloud-client-example/mbed-os/tools/build_api.py", line 380, in _fill_header
    header.puts(start, struct.pack(fmt, time()))
struct.error: required argument is not an integer

reason: time() returns a float. So the fix is to force it to be an int.

Pull request type

[x] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Breaking change

[studavekar]

/morph build

[mbed-ci]

Build : FAILURE

Build number : 3262
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/8330/

[cmonr]

PR was hit by network license issue early last week. Will restart when able.

[cmonr]

/morph export-build

[cmonr]

Whoops.

/morph build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 2908
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8330/

[mbed-ci]

Build : SUCCESS

Build number : 3286
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/8330/

Triggering tests

/morph test
/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : FAILURE

Build number : 2911
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8330/

[mbed-ci]

Test : SUCCESS

Build number : 3093
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/8330/3093

[cmonr]

IAR network license issue.

/morph export-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 2920
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8330/