port to freebsd

Hello John,

Please find two patches in this pull request which make manardb compile and pass its tests in a BSD environment (I'm working on an i386 FreeBSD 10.0, but it should work on other BSDs as well). The one patch substitutes a munmap + mmap for Linux's mremap, per your advice in the Portability section of the project page. (the PROTECTION and SHARING arguments have to be stored in the MTAGMAP structure between the call to MTAGMAP-OPEN and a subsequent MTAGMAP-RESIZE). The other patch just fixes a careless mistake in STORE-ALL-SYMBOLS-TEST; it surprises me how this managed to survive unnoticed for five years.

Yours,
 — B. Smilga.