[oe] [oe-core] [v2] gcc-4.7: Refactor gcc-4.7.2 patch files.

[Elvis Dowson]

This commit renames and re-orders the gcc-4.7.2 recipe patch
files. The patch files are now git am'able, so that you can
directly apply these patches to a local copy of the gcc
git repository, to develop futher patches for the gcc-4.7
recipe.