--- a/libbacktrace/configure.ac	Thu Oct 25 07:37:49 2018 +0900
+++ b/libbacktrace/configure.ac	Thu Feb 13 11:34:05 2020 +0900
@@ -1,5 +1,5 @@
 # configure.ac -- Backtrace configure script.
-# Copyright (C) 2012-2018 Free Software Foundation, Inc.
+# Copyright (C) 2012-2020 Free Software Foundation, Inc.
 
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
@@ -29,7 +29,6 @@
 # IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 # POSSIBILITY OF SUCH DAMAGE.
 
-AC_PREREQ(2.64)
 AC_INIT(package-unused, version-unused,, libbacktrace)
 AC_CONFIG_SRCDIR(backtrace.h)
 AC_CONFIG_HEADER(config.h)
@@ -79,6 +78,9 @@
 "") AC_MSG_ERROR([can't build without awk]) ;;
 esac
 
+AC_CHECK_PROG(DWZ, dwz, dwz)
+AM_CONDITIONAL(HAVE_DWZ, test "$DWZ" != "")
+
 LT_INIT
 AM_PROG_LIBTOOL
 
@@ -257,6 +259,7 @@
 *)     elfsize=unused
 esac
 AC_DEFINE_UNQUOTED([BACKTRACE_ELF_SIZE], [$elfsize], [ELF size: 32 or 64])
+AM_CONDITIONAL(HAVE_ELF, test "$FORMAT_FILE" = "elf.lo")
 
 # XCOFF defines.
 xcoffsize=
@@ -290,10 +293,8 @@
     # simply assume that if we have mman.h, we have mmap.
     have_mmap=yes
     case "${host}" in
-    spu-*-*|*-*-msdosdjgpp)
-        # The SPU does not have mmap, but it has a sys/mman.h header file
-        # containing "mmap_eaddr" and the mmap flags, confusing the test.
-        # DJGPP also has sys/man.h, but no mmap
+    *-*-msdosdjgpp)
+        # DJGPP has sys/man.h, but no mmap
 	have_mmap=no ;;
     esac
   else
@@ -305,12 +306,12 @@
   ALLOC_FILE=alloc.lo
 else
   VIEW_FILE=mmapio.lo
-  AC_PREPROC_IFELSE([
+  AC_PREPROC_IFELSE([AC_LANG_SOURCE([
 #include <sys/mman.h>
 #if !defined(MAP_ANONYMOUS) && !defined(MAP_ANON)
   #error no MAP_ANONYMOUS
 #endif
-], [ALLOC_FILE=mmap.lo], [ALLOC_FILE=alloc.lo])
+])], [ALLOC_FILE=mmap.lo], [ALLOC_FILE=alloc.lo])
 fi
 AC_SUBST(VIEW_FILE)
 AC_SUBST(ALLOC_FILE)
@@ -330,12 +331,6 @@
     # When built as a GCC target library, we can't do a link test.
     AC_EGREP_HEADER([dl_iterate_phdr], [link.h], [have_dl_iterate_phdr=yes],
 		    [have_dl_iterate_phdr=no])
-    case "${host}" in
-    *-*-solaris2.10*)
-        # Avoid dl_iterate_phdr on Solaris 10, where it is in the
-    	# header file but is only in -ldl.
-	have_dl_iterate_phdr=no ;;
-    esac
   else
     AC_CHECK_FUNC([dl_iterate_phdr], [have_dl_iterate_phdr=yes],
 		  [have_dl_iterate_phdr=no])
@@ -367,7 +362,6 @@
 if test -n "${with_target_subdir}"; then
    case "${host}" in
    *-*-mingw*) have_fcntl=no ;;
-   spu-*-*) have_fcntl=no ;;
    *) have_fcntl=yes ;;
    esac
 else
@@ -414,7 +408,7 @@
 [libgo_cv_lib_pthread],
 [CFLAGS_hold=$CFLAGS
 CFLAGS="$CFLAGS -pthread"
-AC_COMPILE_IFELSE([[int i;]],
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([int i;])],
 [libgo_cv_lib_pthread=yes],
 [libgo_cv_lib_pthread=no])
 CFLAGS=$CFLAGS_hold])
@@ -426,6 +420,17 @@
 
 AM_CONDITIONAL(HAVE_PTHREAD, test "$libgo_cv_lib_pthread" = yes)
 
+dnl Test whether the compiler supports the -gdwarf-5 option.
+AC_CACHE_CHECK([whether -gdwarf-5 is supported],
+[libbacktrace_cv_lib_dwarf5],
+[CFLAGS_hold=$CFLAGS
+CFLAGS="$CFLAGS -gdwarf-5"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([int i;])],
+[libbacktrace_cv_lib_dwarf5=yes],
+[libbacktrace_cv_lib_dwarf5=no])
+CFLAGS=$CFLAGS_hold])
+AM_CONDITIONAL(HAVE_DWARF5, test "$libbacktrace_cv_lib_dwarf5" = yes)
+
 AC_CHECK_LIB([z], [compress],
     [AC_DEFINE(HAVE_ZLIB, 1, [Define if -lz is available.])])
 AM_CONDITIONAL(HAVE_ZLIB, test "$ac_cv_lib_z_compress" = yes)
@@ -443,6 +448,7 @@
 
 AC_ARG_VAR(OBJCOPY, [location of objcopy])
 AC_CHECK_PROG(OBJCOPY, objcopy, objcopy,)
+AC_CHECK_PROG(READELF, readelf, readelf)
 AC_CACHE_CHECK([whether objcopy supports debuglink],
 [libbacktrace_cv_objcopy_debuglink],
 [if test -n "${with_target_subdir}"; then
@@ -470,6 +476,7 @@
 fi
 
 AC_CONFIG_FILES(Makefile backtrace-supported.h)
+AC_CONFIG_FILES(install-debuginfo-for-buildid.sh, chmod +x install-debuginfo-for-buildid.sh)
 
 # We need multilib support, but only if configuring for the target.
 AC_CONFIG_COMMANDS([default],