kamailio-5.x: remove "-funroll-loops"

kamailio-5.x: remove "-funroll-loops"

Since recent commit 60ea8ff OpenWrt flags are added to CC_EXTRA_OPTS
instead of CFLAGS, allowing upstream flags to pass into our builds.
Upstream passes "-funroll-loops", which increases package sizes
significantly.

Example mips:

kamailio5_5.3.3-1_mips_24kc.ipk: 1019K
kamailio5_5.3.3-2_mips_24kc.ipk: 1,4M

This commit removes "-funroll-loops", reducing the size to previous
level.

kamailio5_5.3.3-2_mips_24kc.ipk: 1021K

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>