Building static for mac with specific png lib

[mattsfrey]

Hello,
I am doing a static build for mac and have had mostly success at this point other
than being able to link in the correct png delegate.
I have the latest png delegate download stored in ImageMagick-6.8.7-9/png
and have configured / built it with:

./configure --disable-shared --enable-static=yes

and then configured / built IM with:

./configure --disable-shared --enable-static=yes --enable-delegate-build --prefix=/ImageMagick-6.8.7-9

No matter what I do the configure/build is always picking up the libpng15 stored in my system, not the lingpng16.a in ImageMagick/png/.libs

During the configure tests libpng17 and libpng16 are not found

Any suggestions on how to specify for it to statically build with the correct lib?