adb "Permission denied" to run a "./configure" file
This is due to 2 things:


The file does not have execute permissions [AND]
The file cannot gain executable permissions as it is on the SD Card. The SD Card's filesystem can accept file permissions, however it is mounted with the noexec flag, as stated in a comment. This stops files being executed.


Solution:


Copy the net-snmp-5.7.2 directory to the /data/local/tmp directory as root. 
Set the configure file to be executable by running chmod 0777 /data/local/tmp/net-snmp-5.7.2/configure as root.
You should now be able to execute the configure script by typing /data/local/tmp/net-snmp-5.7.2/configure and pressing enter.


Note

This should all be done as the root user :)