Consult libpng-config more consistently.

This is mainly for simplicity, but it should also avoid
some future problems like the ones we recently had with NetBSD.
* configure.ac (LIBPNG): Configure after LIBZ.  Use libpng-config
for cflags, too.  Append -lz if we're not already doing that with
LIBZ.  Do not bother appending -lm, since we always append that.
Coalesce some duplicate code.
* src/Makefile.in (PNG_CFLAGS): New var.
(ALL_CFLAGS): Use it.
* src/image.c [HAVE_PNG]: Don't worry about <libpng/png.h>, as
CFLAGS now handles this.

Fixes: debbugs:17339

1 files changed, 5 insertions, 11 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index e06163c32ce..01569db30e6 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,8 +1,10 @@
 2014-05-04  Paul Eggert  <eggert@cs.ucla.edu>
 
-        Revert recent libpng changes (Bug#17339).
-        * Makefile.in (PNG_CFLAGS): Remove; all uses removed.
-        * image.c [HAVE_LIBPNG_PNG_H]: Include <libpng/png.h>, not <png.h>.
+        Consult libpng-config more consistently (Bug#17339).
+        * Makefile.in (PNG_CFLAGS): New var.
+        (ALL_CFLAGS): Use it.
+        * image.c [HAVE_PNG]: Don't worry about <libpng/png.h>, as
+        CFLAGS now handles this.
 
 2014-05-03  Paul Eggert  <eggert@cs.ucla.edu>
 
@@ -15,14 +17,6 @@
 
         * buffer.c (overlay_strings): Fix the wording of the commentary.
 
-2014-05-02  Paul Eggert  <eggert@cs.ucla.edu>
-
-        Consult libpng-config more consistently (Bug#17339).
-        * Makefile.in (PNG_CFLAGS): New var.
-        (ALL_CFLAGS): Use it.
-        * image.c [HAVE_PNG]: Don't worry about <libpng/png.h>, as
-        CFLAGS now handles this.
-
 2014-05-01  Glenn Morris  <rgm@gnu.org>
 
         * floatfns.c (Fisnan):