Fix failing distcheck about connectedhomeip

[gerickson]

@sagar-apple, the 'distcheck' target does the following:

• make dist
• unarchives the distribution created by 'make dist'
• runs 'make check'
• runs 'make install'
• runs 'make uninstall'

and validates that all of that completes. It's basically a project sanity check.

Typically, the error is that a source file or header file was not listed in a *_SOURCES, *_HEADERS, *_DIST, DIST, or EXTRA_DIST variable and, therefore, was not included in the 'make dist' step and could then not be found for the subsequent steps.

[sagar-apple]

@gerickson @turon I could use some pointers.

[sagar-apple]

STR:

$ make -f Makefile-Standalone distcheck

https://github.com/sagar-apple/connectedhomeip/runs/536893131

[sagar-apple]

@gerickson specifically it fails here. The file it's looking for exists and was created via configure as a step of distcheck.

configure: creating ./config.status
config.status: creating Makefile
config.status: creating third_party/Makefile
config.status: creating third_party/lwip/Makefile
config.status: creating src/Makefile
config.status: creating src/ble/Makefile
config.status: creating src/lwip/Makefile
config.status: error: cannot find input file: `src/lwip/tests/Makefile.in'
Makefile:906: recipe for target 'distcheck' failed

[gerickson]

This is a similar failure as the src/platform/Makefile.in failure from the other day.

Actually, it looks like e26cd7a introduced this issue by deleting tests from SUBDIRS. Basically, the project no longer references that directory and so it gets pruned in 'make dist'. If we aren't going to build those tests, then that subdirectory needs to be specified as

EXTRA_DIST = tests

[sagar-apple]

Yup, that was it. I've added the sub_dirs back for now. We might get rid of the tests folder later on.