[ARC] Add new linker emulation for nps

[ARC] Add new linker emulation for nps

The arc700 nps variant uses some specific named sections to
facilitate its CMEM based instructions, which operate on memory
regions fixed at specific addresses.

This commit adds the arclinux_nps emulation, which is based on the
arclinux emulation. The new emulation uses the OTHER_SECTIONS
variable in the emulation parameters script to provide symbols
mapping to various locations in the CMEM space on nps.

The accompanying test ensures that all symbols are provided at the
correct address in the linker script.

ld/ChangeLog:

  * Makefile.am: Add earclinux_nps.c target and add to
  ALL_EMULATION_SOURCES.
  * Makefile.in: Likewise, regenerated.
  * configure.tgt: Add arclinux_nps as an extra emulation for
  arc*-*-elf* and arc*-*-linux*.
  * emulparams/arc-nps.sh: New file.
  * emulparams/arclinux_nps.sh: New file.
  * testsuite/ld-arc/arclinux-nps.d,
  * testsuite/ld-arc/arclinux-nps.s: New test.