[Bug 18568] New: MacOS X: png.h/libpng is not detected

http://bugs.winehq.org/show_bug.cgi?id=18568

Summary: MacOS X: png.h/libpng is not detected
           Product: Wine
           Version: 1.1.21
          Platform: Macintosh
        OS/Version: Mac OS X 10.5
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P2
         Component: build-env
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

wine's configure fails to detect png.h and libpng although they are present on
Mac OS X -- at least on my 10.5.7 + XCode3 (install DVD) + XQuartz 2.3.3.2
system void of Fink or Macport.

The maybe unusual property is that they are located in /usr/X11/include/ and
/usr/X11/lib/, instead of /usr/include or /usr/lib on Ubuntu Linux.

configure:6223: checking png.h usability
configure:6240: gcc -m32 -c -g -O2  conftest.c >&5
conftest.c:80:17: error: png.h: No such file or directory

Alas, ./configure checks for X only much later than it attempts to use png --
how to add the necessary -I -L before that time?