WPA_TRACE=y can now be used to enable internal backtrace support that
will provide more details about implementation errors, e.g., when some
resources are not released correctly. In addition, this will print out
a backtrace automatically if SIGSEGV is received.
This allows libeap.a and libeap.so to be built by merging in multiple
libraries from src subdirectories. In addition, this avoids wasting
extra space and time for local builds.