* Makefile.in (TARGET_SYSTEM_ROOT, TARGET_SYSTEM_ROOT_DEFINE): New

	* Makefile.in (TARGET_SYSTEM_ROOT, TARGET_SYSTEM_ROOT_DEFINE): New
	variables.
	(main.o): Custom rule which uses $(TARGET_SYSTEM_ROOT_DEFINE).
	* configure.in: Add --with-sysroot.
	* configure: Regenerated.
	* main.c (gdb_sysroot): New variable.
	(captured_main): Initialize gdb_sysroot.
	* defs.h (gdb_sysroot): New extern declaration.
	* solib.c (_initialize_solib): Initialize solib_absolute_prefix.