mklibgcc.in: Add logic to handle $DFP_ENABLE and $DFP_CFLAGS.

mklibgcc.in: Add logic to handle $DFP_ENABLE and $DFP_CFLAGS.

	* mklibgcc.in: Add logic to handle $DFP_ENABLE and $DFP_CFLAGS.
	Compile dfp-bit.c from the source directory using -DWIDTH and
	$DFP_CFLAGS to control the compilation of that file, rather than
	generating width-specific versions in the build directory.
	* Makefile.in (libgcc.mk): Pass down DFP_ENABLE and DFP_CFLAGS.
	(LIBGCC_DEPS): Replace $(D32PBIT) et al with config/dfp-bit.[hc].

From-SVN: r111595