Configure ends up with error even if libudev is installed.

Greetings,
I run configure script with the following parameters `CFLAGS="-m32 -mstackrealign -fPIC" --prefix="$PWD" --disable-shared` and it terminates with :
```
checking for libudev.h... no
configure: error: udev support requested but libudev header not installed
```

PS: if I run it only with `./configure --prefix=/usr --disable-static` it runs like a charm.