Increase BERI loader section alignment to 16

The .text, .bss, and .data sections claimed 16-byte alignment, but were
only aligned to 8 by the linker script.

Discovered with strip(1) from elftoolchain, which performs validation
absent from the binutils strip(1).

Sponsored by:	DARPA, AFRL


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275457 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f