proxy-libintl_20100902.bb: Specify -fPIC in CFLAGS

Some architectures like mips become upset if you
try to link non-pic libraries to shared objects
some generate pic by default so it does not matter
Specifying -fPIC on commandline should make all happy

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>