Add dwarf support

The new gcc12 release does not support stabs any more.
This was a good reason to add support for dwarf.

The stabs code still works and is used if configure option --dwarf
is not used.

Tested on x86_64, i386, arm, arm64, riscv64 with dwarf-5.
Some debuggers may not support dwarf-5. Try using older dwarf versions
i that case.
The tccmacho.c code probably need some support for dwarf.

arm-gen.c, arm64-gen.c, i386-gen.c, riscv64-gen.c, x86_64-gen.
- fix get_sym_ref symbol size

arm-link.c, arm64-link.c, i386-link.c, riscv64-link.c, x86_64-link.c
- add R_DATA_32U

libtcc.c:
- parse -gdwarf option

tcc.c:
- add dwarf option

tcc.h:
- add dwarf option and sections

tccelf.c:
- init dwarf sections
- avoid adding sh_addr for dwarf sections
- remove dwarf relocs for output dll
- add dwarf sections for tccrun

tccgen.c:
- add dwarf defines + global data
- add dwarf_* functions
- mix dwarf code with stabs code
- a trick is used to emit function name in .debug_line section so
  only this section has to be parsed instead of .debug_info and
  .debug_abbrev.
- fix init debug_modes

tccrun.c:
- add dwarf sections in rt_context
- init them in tcc_run
- add new dwarf code rt_printline_dwarf to find file/function

dwarf.h:
- New file

tcc-doc.texi:
- document dwarf

configure:
- add dwarf option

lib/Makefile
- change -gstabs into -gdwarf

lib/bt-exe.c, tests/tests2/Makefile, tests/tests2/126_bound_global:
- Add __bound_init call
- Add new testcase to test it

libtcc.c

@@ -1722,6 +1722,12 @@ static void args_parser_listfile(TCCState *s,
     *pargc = s->argc = argc, *pargv = s->argv = argv;
 }
 
+#ifdef CONFIG_DWARF
+#define	DWARF_VERSION	atoi(CONFIG_DWARF)
+#else
+#define	DWARF_VERSION	0
+#endif
+
 PUB_FUNC int tcc_parse_args(TCCState *s, int *pargc, char ***pargv, int optind)
 {
     TCCState *s1 = s;
@@ -1819,6 +1825,7 @@ reparse:
             s->rt_num_callers = atoi(optarg);
             s->do_backtrace = 1;
             s->do_debug = 1;
+	    s->dwarf = DWARF_VERSION;
             break;
 #endif
 #ifdef CONFIG_TCC_BCHECK
@@ -1826,16 +1833,22 @@ reparse:
             s->do_bounds_check = 1;
             s->do_backtrace = 1;
             s->do_debug = 1;
+	    s->dwarf = DWARF_VERSION;
             break;
 #endif
         case TCC_OPTION_g:
             /* Use "-g" as alias for "-g1". Use "-g0" to disable debug */
             /* Other common used values: "-g0", "-g1", "-g2" and "-g3" */
             /* no failure with unsupported options */
-            if (isnum(*optarg))
+            s->do_debug = 1;
+	    s->dwarf = DWARF_VERSION;
+	    if (*optarg == 'd') {
+		s->dwarf = 5;
+		if (!strncmp(optarg,"dwarf-",6))
+                    s->dwarf = atoi(optarg + 6);
+	    }
+            else if (isnum(*optarg))
                 s->do_debug = atoi(optarg);
-            else
-                s->do_debug = 1;
             break;
         case TCC_OPTION_c:
             x = TCC_OUTPUT_OBJ;