Add support for a minimal version of libgfortran for accelerator targets.
* Makefile.am (AM_CFLAGS): Add -DLIBGFOR_MINIMAL if LIBGFOR_MINIMAL.
(gfor_io_src, gfor_heper_src, gfor_src): Split into minimal and
always included sources.
* Makefile.in: Regenerate.
* configure.ac (LIBGFOR_MINIMAL): New AM_CONDITIONAL.
* configure: Regenerate.
* caf/single.c (caf_runtime_error): Don't print messages if
LIBGFOR_MINIMAL.
* runtime/compile_options.c (fatal_error_in_progress,
show_signal, backtrace_handler, maybe_find_addr2line): Guard with
!defined LIBGFOR_MINIMAL.
(set_options): Likewise for the backtrace code.
* runtime/minimal.c: New file.
From-SVN: r218170
ee95f9288a