sim --enable-cgen-maint

I had reason yesterday to want to regenerate configury files which I
do with --enable-maintainer-mode, and added --enable-cgen-maint
accidentally.  The first problem I hit is that sim looks for cgen in a
different directory by default than opcodes, and I had my source
layout set up for opcodes rather than sim.  Fix that by making both
use ../cgen first, then ../../cgen relative to sim/ and opcodes/.  The
next problem was that various sim local.mk files expected generated
sources in the build dir rather than the source dir.  Fix that by
adding $(srcdir) to paths.  Finally, the generated iq2000 files had a
compile error, fixed by the cpu/iq2000.cpu patch.

cpu/
	* iq2000.cpu (syscall): Add pc arg.
opcodes/
	* configure.ac (cgendir): Default to ../../cgen, but use ../cgen
	if found there.
	* configure: Regenerate.
sim/m4/
	* sim_ac_option_cgen_maint.m4 (cgendir): Look in ../cgen too.
sim/
	* cris/local.mk: Add $(srcdir) to paths for regenerated source.
	* frv/local.mk: Likewise.
	* iq2000/local.mk: Likewise.
	* lm32/local.mk: Likewise.
	* m32r/local.mk: Likewise.
	* or1k/local.mk: Likewise.
	* Makefile.in: Regenerate.
	* configure: Regenerate.

cpu/iq2000.cpu

@@ -1059,7 +1059,7 @@
 (dni syscall "system call" (YIELD-INSN)
      "syscall"
      (+ OP_SPECIAL execode (f-func 12))
-     (c-call VOID "do_syscall")
+     (c-call VOID "do_syscall" pc)
      ())
 
 ; Macro instructions, common to iq10 & iq2000