Merge: Perfize nitcc_runtime

Slight improvement of the work of nitcc.

Numbers with raw parsing of a 30MB json file from nitrpg (only the AST creation, no further analysis)

Before: 0m5.700s ; 25.1 GIr
After: 0m3.540s (-38%) ; 20.3 GIr (-19%)

There is still a lot (99?) of improvements to make before having reasonable numbers, but the nitcc_runtime part ain't one.

Pull-Request: #1876
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>