Nodejs bindings follow config settings

[gabrielschulhof]

If you configure soletta to not have OIC functionality then the resulting node.js bindings can't have such functionality either.

Addtitionally, this PR fixes #1567 by surrounding the addition of the fortify-related CFLAGS with a check to make sure that -O0 is not already part of the CFLAGS.

[bdilly]

Does it make sense to have a release build with -O0 ?

[gabrielschulhof]

Well, I've tried building with

BUILD_TYPE_RELEASE=n make

and it seems to ignore that, whereas building with

COMMON_CFLAGS="-g -O0" make

correctly prepends -g -O0 to the COMMON_CFLAGS.

The bottom line is that COMMON_CFLAGS may be set from outside the build environment, so the build environment has to account for this. Now, most of the time the COMMON_CFLAGS arriving from the outside are orthogonal to what we're adding inside the build environment, but in this case the existing COMMON_CFLAGS need to take precedence.

[gabrielschulhof]

Additional info: The use case for this is the situation where the user starts the build process with
npm install or npm install --debug. In both cases the npm install process ends up calling make alldefconfig followed by make, but prefixed with a bunch of configuration options. In case of npm install, it results in

USE_NODEJS="y" RPATH="y" make

whereas in the npm install --debug case it also has to at least turn on -g -O0 in Soletta. It does this by also adding COMMON_CFLAGS="-g -O0" to the settings preceding the make.

I also don't necessarily want to link Soletta's debug build feature to node.js' debug build, considering -g -O0 as sufficient debugging support by Soletta for the node.js bindings.

Here's how it is currently:

soletta/bindings/nodejs/build-for-npm.sh

Lines 28 to 34 in 5daa00e

	make alldefconfig || exit 1
	if test "x${npm_config_debug}x" = "xtruex"; then
	sed -i .config -r -e 's/(# )?CONFIG_CFLAGS.*$/CONFIG_CFLAGS="-g -O0"/'
	fi
	USE_NODEJS="y" RPATH="y" make || exit 1

There are two problems with how it is currently:

1. It modifies the .config file. This is fixed in this PR by conditionally setting COMMON_CFLAGS for make instead.
2. -O0 from external COMMON_CFLAGS is being overridden by RELEASE_COMMON_CFLAGS which later adds -O2 so as to support -DFORTIFY_SOURCE=2. This currently cannot be avoided by either modifying .config or by prefixing make with a variable AFAICT.

[gabrielschulhof]

OK, so I understand why I can't use BUILD_TYPE_RELEASE=n make. It's because Makefile includes .config, and in .config BUILD_TYPE_RELEASE is set explicitly to y, not via ?=, so the environment variable is being ignored. Thus, my only option, if I wish not to modify the .config file is to use COMMON_CFLAGS which, in turn, leaves me with the solution in this PR.

[bdilly]

What I'm suggesting is to use BUILD_TYPE_DEBUG=y instead of BUILD_TYPE_RELEASE=y (on this case BUILD_TYPE_RELEASE isn't even declared)