trap for bcmatch installed is missed

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What steps will reproduce the problem?
1. run amqp on an installation without bcmath installed.

What is the expected output? 
"bc math extention to pho is not installed but is required by php amqp"

What do you see instead?
"bcmod is an undedfined function"

What version of the product are you using? 0.8 On what operating system? centos


Please provide any additional information below.
I recommend moving the test to the top of the -wire file, where it can't be 
missed, if the test fails, issue a message and exit. No point in throwing an 
exception. Just tell user why and stop.

Original issue reported on code.google.com by [email protected] on 15 Aug 2011 at 11:28