libbacktrace: Reapply Rust-specific changes

New:
Fix for #28447

Merged:
openbsd support: fcb30a0
bitrig integration: cd8f317

Not merged:
d4fc3ec
@Diggsey says this change was unintended (#30666 (comment))

src/libbacktrace/configure

@@ -5691,7 +5691,7 @@ else
     lt_cv_sys_max_cmd_len=8192;
     ;;
 
-  netbsd* | freebsd* | openbsd* | darwin* | dragonfly*)
+  netbsd* | freebsd* | openbsd* | darwin* | dragonfly* | bitrig*)
     # This has been around since 386BSD, at least.  Likely further.
     if test -x /sbin/sysctl; then
       lt_cv_sys_max_cmd_len=`/sbin/sysctl -n kern.argmax`
@@ -9374,7 +9374,7 @@ if test -z "$aix_libpath"; then aix_libpath="/usr/lib:/lib"; fi
       ;;
 
     # FreeBSD 3 and greater uses gcc -shared to do shared libraries.
-    freebsd* | dragonfly*)
+    freebsd* | dragonfly* | openbsd* | bitrig*)
       archive_cmds='$CC -shared -o $lib $libobjs $deplibs $compiler_flags'
       hardcode_libdir_flag_spec='-R$libdir'
       hardcode_direct=yes

src/libbacktrace/ltmain.sh

@@ -4741,7 +4741,7 @@ func_mode_link ()
 	    # These systems don't actually have a C library (as such)
 	    test "X$arg" = "X-lc" && continue
 	    ;;
-	  *-*-openbsd* | *-*-freebsd* | *-*-dragonfly*)
+	  *-*-openbsd* | *-*-freebsd* | *-*-dragonfly* | *-*-bitrig*)
 	    # Do not include libc due to us having libc/libc_r.
 	    test "X$arg" = "X-lc" && continue
 	    ;;

src/libbacktrace/pecoff.c

@@ -602,7 +602,7 @@ coff_add (struct backtrace_state *state, int descriptor,
   const b_coff_section_header *sects;
   struct backtrace_view str_view;
   int str_view_valid;
-  size_t str_size;
+  uint32_t str_size;
   off_t str_off;
   struct backtrace_view syms_view;
   off_t syms_off;