zlib does not build zlib.dylib when changing build_arch

[ryandesign (Ryan Carsten Schmidt)]

If I set build_arch to i386 on 64-bit Snow Leopard, zlib installs without complaint, but doesn't build any dylibs.

$ /opt/local/bin/port contents zlib
Port zlib contains:
  /opt/local/include/zconf.h
  /opt/local/include/zlib.h
  /opt/local/lib/libz.1.2.3.dylib
  /opt/local/lib/libz.1.dylib
  /opt/local/lib/libz.a
  /opt/local/lib/libz.dylib
  /opt/local/share/doc/zlib-1.2.3/ChangeLog
  /opt/local/share/doc/zlib-1.2.3/examples/example.c
  /opt/local/share/doc/zlib-1.2.3/examples/fitblk.c
  /opt/local/share/doc/zlib-1.2.3/examples/gun.c
  /opt/local/share/doc/zlib-1.2.3/examples/gzappend.c
  /opt/local/share/doc/zlib-1.2.3/examples/gzjoin.c
  /opt/local/share/doc/zlib-1.2.3/examples/gzlog.c
  /opt/local/share/doc/zlib-1.2.3/examples/gzlog.h
  /opt/local/share/doc/zlib-1.2.3/examples/README.examples
  /opt/local/share/doc/zlib-1.2.3/examples/zlib_how.html
  /opt/local/share/doc/zlib-1.2.3/examples/zpipe.c
  /opt/local/share/doc/zlib-1.2.3/examples/zran.c
  /opt/local/share/doc/zlib-1.2.3/FAQ
  /opt/local/share/doc/zlib-1.2.3/README
  /opt/local/share/man/man3/zlib.3.gz

$ /32mp/bin/port contents zlib
Port zlib contains:
  /32mp/include/zconf.h
  /32mp/include/zlib.h
  /32mp/lib/libz.a
  /32mp/share/doc/zlib-1.2.3/ChangeLog
  /32mp/share/doc/zlib-1.2.3/examples/example.c
  /32mp/share/doc/zlib-1.2.3/examples/fitblk.c
  /32mp/share/doc/zlib-1.2.3/examples/gun.c
  /32mp/share/doc/zlib-1.2.3/examples/gzappend.c
  /32mp/share/doc/zlib-1.2.3/examples/gzjoin.c
  /32mp/share/doc/zlib-1.2.3/examples/gzlog.c
  /32mp/share/doc/zlib-1.2.3/examples/gzlog.h
  /32mp/share/doc/zlib-1.2.3/examples/README.examples
  /32mp/share/doc/zlib-1.2.3/examples/zlib_how.html
  /32mp/share/doc/zlib-1.2.3/examples/zpipe.c
  /32mp/share/doc/zlib-1.2.3/examples/zran.c
  /32mp/share/doc/zlib-1.2.3/FAQ
  /32mp/share/doc/zlib-1.2.3/README
  /32mp/share/man/man3/zlib.3.gz

[ryandesign (Ryan Carsten Schmidt)]

On i386 the configure script says

Checking for shared library support...
No shared library support; try without defining CC and CFLAGS

whereas on x86_64 it says

Checking for shared library support...
Building shared library libz.1.2.3.dylib with /usr/bin/gcc-4.2.

[ryandesign (Ryan Carsten Schmidt)]

Fixed zlib in r57032, but any other port that depends on zlib that was built after zlib @1.2.3_2 was built with build_arch i386 will be linking with the OS copy of zlib and needs to be rebuilt.