net-mgmt/statsite: Fix build with GCC 4.2 (gnu89 by default)

/nxb-bin/usr/bin/cc -O2 -pipe -G0 -EB -mabi=64 -msoft-float -fno-strict-aliasing -c ./MurmurHash3.c -o ./MurmurHash3.o
./MurmurHash3.c: In function 'MurmurHash3_x64_128':
./MurmurHash3.c:66: error: 'for' loop initial declaration used outside C99 mode

http://beefy16.nyi.freebsd.org/data/120mips64-quarterly/484420/logs/statsite-0.8.0_2.log