Compile Node.js with -Os flag

[sr229]

According to nodejs/node#19, it seems that its possible to make Node.js more memory efficient by swapping -O3 to -Os. As @bnoordhuis stated:

There is an --optimize_for_size flag in newer versions of node and you can limit the size of the heap with --max_old_space_size=... (and --max_semi_space_size and --max_executable_size) in all versions.

You can also tweak common.gypi to build at -Os instead of -O3. The smaller binary, besides using less memory, also tends to run faster on systems with small L1 code caches.

Therefore this should compliment ARM support because most ARM boards are very memory-limited.

[deansheather]

What's the catch? Slower performance on regular computers?

[sr229]

@deansheather it should be more faster with larger L1 caches so I think we can go with this route.