* Reduce (half) the number of loads emitted for calling into C code

* Reduce (half) the number of loads emitted for calling into C code

As after each function call GCC clobbers the pointer to the function
relocation table.  This commit modify the code generation to create a
local copy of it for each function.  This reduces the average number
of loads for each function call into C from two to one.

	* src/comp.c (comp_t): Add 'func_relocs_ptr_type' and
	'func_relocs_local' fields.
	(emit_call): Use the local func_relocs pointer when possible.
	(emit_ctxt_code): Fill 'comp.func_relocs_ptr_type'.
	(compile_function): Declare 'func_relocs_ptr_local'.
	(compile_function): Assign 'func_relocs_ptr_local' from the global
	value in each function prologue.