--- configure.orig	2018-04-25 06:22:23.000000000 +0900
+++ configure	2020-11-21 14:23:23.000000000 +0900
@@ -7215,16 +7215,11 @@
       _lt_dar_allow_undefined='${wl}-undefined ${wl}suppress' ;;
     darwin1.*)
       _lt_dar_allow_undefined='${wl}-flat_namespace ${wl}-undefined ${wl}suppress' ;;
-    darwin*) # darwin 5.x on
-      # if running on 10.5 or later, the deployment target defaults
-      # to the OS version, if on x86, and 10.4, the deployment
-      # target defaults to 10.4. Don't you love it?
+    darwin*)
       case ${MACOSX_DEPLOYMENT_TARGET-10.0},$host in
-	10.0,*86*-darwin8*|10.0,*-darwin[91]*)
-	  _lt_dar_allow_undefined='${wl}-undefined ${wl}dynamic_lookup' ;;
-	10.[012]*)
+	10.[012],*|,*powerpc*)
 	  _lt_dar_allow_undefined='${wl}-flat_namespace ${wl}-undefined ${wl}suppress' ;;
-	10.*)
+	*)
 	  _lt_dar_allow_undefined='${wl}-undefined ${wl}dynamic_lookup' ;;
       esac
     ;;
@@ -18088,7 +18083,7 @@
 if test "Z$ga_supplib_dir" != "Z" ; then
   echo looking in $ga_supplib_dir for additional dependent libs
 
-  # png15
+  # png
   echo
   echo png
   echo ---
@@ -18105,13 +18100,13 @@
   LDFLAGS="-L${ga_supplib_dir}/lib "
   LIBS="$LIBS "
 
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for main in -lpng15" >&5
-$as_echo_n "checking for main in -lpng15... " >&6; }
-if ${ac_cv_lib_png15_main+:} false; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for main in -lpng" >&5
+$as_echo_n "checking for main in -lpng... " >&6; }
+if ${ac_cv_lib_png_main+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lpng15  $LIBS"
+LIBS="-lpng  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -18125,17 +18120,17 @@
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_png15_main=yes
+  ac_cv_lib_png_main=yes
 else
-  ac_cv_lib_png15_main=no
+  ac_cv_lib_png_main=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_png15_main" >&5
-$as_echo "$ac_cv_lib_png15_main" >&6; }
-if test "x$ac_cv_lib_png15_main" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_png_main" >&5
+$as_echo "$ac_cv_lib_png_main" >&6; }
+if test "x$ac_cv_lib_png_main" = xyes; then :
   have_png=yes
 fi
 
@@ -19016,10 +19011,10 @@
 $as_echo "$ac_cv_lib_grib2c_main" >&6; }
 if test "x$ac_cv_lib_grib2c_main" = xyes; then :
    use_grib2=yes
-#        GA_SET_LIB_VAR([grib2_libs], [grib2c jasper png15 z])
+#        GA_SET_LIB_VAR([grib2_libs], [grib2c jasper png z])
 
   ga_lib_prefix='-l'
-  for ga_lib_name in grib2c jasper png15 z ; do
+  for ga_lib_name in grib2c jasper png z ; do
       grib2_libs="$grib2_libs ${ga_lib_prefix}${ga_lib_name}"
   done
 
@@ -19077,13 +19072,13 @@
 $as_echo "$ac_cv_lib_grib2c_main" >&6; }
 if test "x$ac_cv_lib_grib2c_main" = xyes; then :
 
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for main in -lpng15" >&5
-$as_echo_n "checking for main in -lpng15... " >&6; }
-if ${ac_cv_lib_png15_main+:} false; then :
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for main in -lpng" >&5
+$as_echo_n "checking for main in -lpng... " >&6; }
+if ${ac_cv_lib_png_main+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lpng15  $LIBS"
+LIBS="-lpng  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -19097,17 +19092,17 @@
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_png15_main=yes
+  ac_cv_lib_png_main=yes
 else
-  ac_cv_lib_png15_main=no
+  ac_cv_lib_png_main=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_png15_main" >&5
-$as_echo "$ac_cv_lib_png15_main" >&6; }
-if test "x$ac_cv_lib_png15_main" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_png_main" >&5
+$as_echo "$ac_cv_lib_png_main" >&6; }
+if test "x$ac_cv_lib_png_main" = xyes; then :
 
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for compress in -lz" >&5
 $as_echo_n "checking for compress in -lz... " >&6; }
@@ -19212,7 +19207,7 @@
 if test "x$ac_cv_lib_jasper_main" = xyes; then :
 
       ga_check_grib2="yes"
-      G2_LIBS="-lgrib2c -ljasper -lpng15 -lz"
+      G2_LIBS="-lgrib2c -ljasper -lpng -lz"
 
 fi
 
@@ -19451,7 +19446,7 @@
       cairo_inc="$cairo_inc ${ga_include_prefix}/${ga_include_name}"
   done
 
-#          GA_SET_LIB_VAR(cairo_libs, [cairo Xrender fontconfig freetype pixman-1 png15 xml2 z])
+#          GA_SET_LIB_VAR(cairo_libs, [cairo Xrender fontconfig freetype pixman-1 png xml2 z])
 
   ga_lib_prefix='-l'
   for ga_lib_name in cairo ; do