[arduino] An obvious increase of ROM cause building failure

[qiaojingx]

Description

This is a regression issue. ROM samples increase obviously from last commit on arduino 101, some test case fail to build due to ROM problem.

Test Code

test-ocfserver.js;
th02-ocf.js;
test-tcp6-server.js;

Steps to Reproduction

1. make JS=tests/test-ocfserver.js ROM=256
2. Increase ROM and repeat step 1.

Actual Result

Increase ROM from 256-290, build failed due to ' ROM ' overflow.

Increase ROM to 292, build failed due to `FLASH' overflow:

Expected Result

Build each test case successfully.

Test Builds

Branch	Commit Id	Target Device	Test Date	Result
master	f90d9d1	arduino 101	May 24, 2018	Pass
master	2b033e1	arduino 101	Jun 12, 2018	Fail

Additional Information

ROM=256 is not suitable for most of samples and tests.

[qiaojingx]

Verified with commit 2b033e1 + #1889. This issue is fixed.
This issue will be closed after patch #1889 merged.