The symptoms are like so:
bash: ./configure: /bin/sh: bad interpreter: Permission denied
Which has nothing whatever to do with the root cause. The actual problem is that pecl downloads files to /tmp and does its work there. If /tmp is mounted as noexec, pecl will fail with errors like the one above.
Solution #1: Change the fstab for /tmp, removing the noexec option.
Solution #2: Working in another directory – such as /usr/src – manually perform the steps pecl automates. An example for xdebug is found here.