building from src, linking libpng

I'm trying to build GraphicsMagick from src w/o X11 support, but with png support. The ./configure process tests for libpng library and headers (finds successfully), then does a link test trying to call png_get_io_ptr().

I've run nm(1) on libpng.so, and it says there -is- a png_get_io_ptr(), but the test is still failing:

[snip]
checking for PNG support ... 
checking png.h usability... yes
checking png.h presence... yes
checking for png.h... yes
checking for png_get_io_ptr in -lpng... no
checking if PNG package is complete... no -- some components failed test
[snip]


Am looking into it, but through I'd pass the issue out to the broader
world as well, in case somebody beats me to answer.

-bch

-- 
Brad Harder
Method Logic Digital Consulting
http://methodlogic.net/
http://twitter.com/bcharder


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