decContext.c, [...]: Add libgcc-style license exception clause.

decContext.c, [...]: Add libgcc-style license exception clause.

	* decContext.c, decContext.h, decDPD.h, decimal128.c,
	decimal128.h, decimal32.c, decimal32.h, decimal64.c, decimal64.h,
	decLibrary.c, decNumber.c, decNumber.h, decNumberLocal.h,
	decRound.c, decRound.h, decUtility.c, decUtility.h: Add
	libgcc-style license exception clause.

From-SVN: r122722