[ARC] Make libgcc compatible with ARC's reduced register set config.

[ARC] Make libgcc compatible with ARC's reduced register set config.

ARC processors can work with a reduced register set (i.e. registers
r4-r9 and r16-r25 are not available). This option can be enabled
passing -mrf16 option to the compiler, or by using -mcpu=em_mini CPU
configuration. Using RF16 config requires all the hand-made assembly
files used in libgcc to have the corresponding RF16 object attribute
set.

This patch qualifies the relevant hand-made assembly files to
RF16 config, and also adds generic c-functions for the one which are
not.

libgcc/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/crti.S: Add RF16 object attribute.
	* config/arc/crtn.S: Likewise.
	* config/arc/crttls.S: Likewise.
	* config/arc/lib1funcs.S: Likewise.
	* config/arc/fp-hack.h (ARC_OPTFPE): Define.
	* config/arc/lib2funcs.c: New file.
	* config/arc/t-arc: Add lib2funcs to LIB2ADD.