[libpng16] Make autogen.sh work with automake 1.13 as well as 1.14. Do this

by always removing the 1.14 'compile' script but never checking for it.
diff --git a/ANNOUNCE b/ANNOUNCE
index f85824a..86e97ac 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.6.7beta02 - October 5, 2013
+Libpng 1.6.7beta02 - October 6, 2013
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -46,7 +46,7 @@
     was never implemented.
   Merged pngunknown.c with 1.7 version and back ported 1.7 improvements/fixes
 
-Version 1.6.7beta02 [October 5, 2013]
+Version 1.6.7beta02 [October 6, 2013]
   Made changes for compatibility with automake 1.14:
     1) Added the 'compile' program to the list of programs that must be cleaned
        in autogen.sh
@@ -69,6 +69,8 @@
     useful side effect of avoiding a bogus warning generated by the latest
     version of the Intel C compiler (it objects to
     condition ? string-literal : string-literal).
+  Make autogen.sh work with automake 1.13 as well as 1.14. Do this by always
+    removing the 1.14 'compile' script but never checking for it.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 07449bc..d049e36 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4660,7 +4660,7 @@
     was never implemented.
   Merged pngunknown.c with 1.7 version and back ported 1.7 improvements/fixes
 
-Version 1.6.7beta02 [October 5, 2013]
+Version 1.6.7beta02 [October 6, 2013]
   Made changes for compatibility with automake 1.14:
     1) Added the 'compile' program to the list of programs that must be cleaned
        in autogen.sh
@@ -4683,6 +4683,8 @@
     useful side effect of avoiding a bogus warning generated by the latest
     version of the Intel C compiler (it objects to
     condition ? string-literal : string-literal).
+  Make autogen.sh work with automake 1.13 as well as 1.14. Do this by always
+    removing the 1.14 'compile' script but never checking for it.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/autogen.sh b/autogen.sh
index 6d674d9..ccbfad6 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -74,8 +74,11 @@
 #
 # The autotools generated files:
 libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in\
-   config.sub configure depcomp install-sh ltmain.sh missing test-driver\
-   compile"
+   config.sub configure depcomp install-sh ltmain.sh missing test-driver"
+#
+# Files generated by versions of configue >2.68 or automake >1.13 (i.e. later
+# versions than those reqiured by configure.ac):
+libpng_autotools_extra="compile"
 #
 # These are separate because 'maintainer-clean' does not remove them.
 libpng_libtool_files="scripts/libtool.m4 scripts/ltoptions.m4\
@@ -95,6 +98,7 @@
 # of Makefile.  These functions do the two bits of cleaning.
 clean_autotools(){
    rm -rf $libpng_autotools_files $libpng_libtool_files $libpng_autotools_dirs
+   rm -rf $libpng_autotools_extra
 }
 
 clean_configure(){