Add Shared library for uClibc toolchain

Done
1: Add  ARC Cross uClibc Target Shared Library in uClibc plugin
2: As Static library,but remove arc-linux-ar as Archiver and add call
arc-linux-gcc as Linker
3: Both for little endian and big endian

Undone:
1: add options specific to shared libraries
2: cannot get .so file
Signed-off-by: Yunlu Zhang <Yunlu.Zhang@synopsys.com>