decRound.c: Move declarations to new file, update comments.

decRound.c: Move declarations to new file, update comments.

libdecnumber/
	* decRound.c: Move declarations to new file, update comments.
	* decRound.h: New file.
gcc/
	* mklibgcc.in: Fix dependencies for dfp-bit.c.
	* config/dfp-bit.h (CONTEXT_ROUND): Delete.
	(DFP_INIT_ROUNDMODE): Define.
	* config/dfp-bit.c: Replace CONTEXT_ROUND with DFP_INIT_ROUNDMODE.

From-SVN: r119329