This is not a query on some topic, its just an informative post.
I have been trying to get wpa_supplicant compiled madly for the last few days. the compilation of several source files ended in undefined symbols of the dynamic linker. After worrying about my glibc, my gcc and my binutils and searching for the problem i had an enlightenment one fine evening:
If the compiler can't link the damn code, is it perhaps the fault of the Makefile? And endeed, the makefile did at no point link to the library in question.
So if you too have trouble compiling wpa_supplicant (I don't recall the version at this point and i'm too lazy to reboot and find out), try adding -ldl to the CFLAGS in the Makefile.
Hope this helps someone someday.