net-snmp: Fix build error ./.libs/libnetsnmpmibs.so: undefined reference to `pthread_...

net-snmp: Fix build error ./.libs/libnetsnmpmibs.so: undefined reference to `pthread_create'

Do not override do_configure and pass endianness information in
EXTRA_OECONF, also move common settings from EXTRA_OECONF in recipes to
inc file.

Let build go in parallel for svn recipe. It works !

Signed-off-by: Khem Raj <raj.khem@gmail.com>