or1k: Support long jump offsets with -mcmodel=large

or1k: Support long jump offsets with -mcmodel=large

The -mcmodel=large option was originally added to handle generation of
large binaries with large PLTs.  However, when compiling the Linux
kernel with allyesconfig the output binary is so large that the jump
instruction 26-bit immediate is not large enough to store the jump
offset to some symbols when linking.  Example error:

  relocation truncated to fit: R_OR1K_INSN_REL_26 against symbol `do_fpe_trap' defined in .text section in arch/openrisc/kernel/traps.o

We fix this by forcing jump offsets to registers when -mcmodel=large.

Note, to get the Linux kernel allyesconfig config to work with OpenRISC,
this patch is needed along with some other patches to the Linux hand
coded assembly bits.

gcc/ChangeLog:

	* config/or1k/predicates.md (call_insn_operand): Add condition
	to not allow symbol_ref operands with TARGET_CMODEL_LARGE.
	* config/or1k/or1k.opt: Document new -mcmodel=large
	implications.
	* doc/invoke.texi: Likewise.

gcc/testsuite/ChangeLog:

	* gcc.target/or1k/call-1.c: New test.
	* gcc.target/or1k/got-1.c: New test.