[cairo] problem building cairo 1.2.6

[tj]

When I try to configure cairo 1.2.6 I get this...

$./configure
.
.
.
checking for cairo's PNG backend...
./configure: line 24784: --exists: command not found
./configure: line 24784: --exists: command not found
./configure: line 24784: --exists: command not found
configure: WARNING: Could not find libpng in the pkg-config search path
checking whether cairo's PNG backend could be enabled... no
configure: error: requested PNG backend could not be enabled

My PKG_CONFIG is set correctly to
$ echo $PKG_CONFIG
/usr/lib/pkgconfig

And:

$ ls -l /usr/lib/pkgconfig/libpng*
lrwxrwxrwx    1 root     root           11 Feb  7  2004 
/usr/lib/pkgconfig/libpng.pc -> libpng12.pc
-rw-r--r--    1 root     root          232 Oct 13  2002 
/usr/lib/pkgconfig/libpng12.pc

I looked at line 24784 in configure and it is a blank line.

So, can a kind soul tell me what my problem is?

tj