nss: updating nss.pc.in to include /usr/include/mozilla/nss directory
ninja-native: adding initial ninja build support for chromium
chromium: adding updated version 24.0.1312.52; refactor build

The chromium build now requires ninja-native to build, as it builds faster than make.
Refactor EXTRA_OEGYP so that it is passed via include.gypi and oe-defaults.gypi files.
This allows for custom per-platform builds. Add support for qemux86 target, as well as
existing armv7a (tested) and armv6 (not tested.)
Merge branch 'master' of https://github.com/ventureresearch/meta-browser

Conflicts:
	recipes-support/nss/nss_3.13.3.bb (PR was 2, should be 3 for nss pc change)