or1k: Fixup exception header data encodings

or1k: Fixup exception header data encodings

While running glibc tests several *-textrel tests failed showing that
relocations remained against read only sections.  It turned out this was
related to exception headers data encoding being wrong.

By default pointer encoding will always use the DW_EH_PE_absptr format.

This patch uses format DW_EH_PE_pcrel and DW_EH_PE_sdata4.  Optionally
DW_EH_PE_indirect is included for global symbols.  This eliminates the
relocations.

gcc/ChangeLog:

	* config/or1k/or1k.h (ASM_PREFERRED_EH_DATA_FORMAT): New macro.