[PSEH3]

- Switch the registration asm functions from a complete custom calling convention to regparm(2), so that it can be used in "returns_twice" based algorithm (required by CLANG, which doesn't support "asm goto" construct)
- Add support for saving all non-volatiles in the registration frame (also required by CLANG, since without asm goto, we cannot give the compiler the required hints to save these registers itself)

svn path=/trunk/; revision=62383