Even if you do have the 10.4 SDK (which I think you might), it's trying to compile using GCC 4.2, which, as the error message says, the 10.4 SDK is not compatible with. The port should not be trying to use the 10.4 SDK.
Actually on my Snow Leopard system (which does have the 10.4u SDK) I get the error:
error: There is no SDK with the name or path '/Developer/SDKs/MacOSX10.3.9.sdk'
[BEROR]error: There is no SDK with the name or path '/Developer/SDKs/MacOSX10.3.9.sdk'
Probably the port should be updated to 0.9.10 too, but doing so doesn't seem to help this. I'll attach my patch anyway as a starting point.