This adds the capability to compile got-portable on FreeBSD.

This commit modifies the GoT main branch to be able to compile it under linux.

Feature requested by naddy. ok naddy, who also suggested some tweaks that will arrive shortly

Known to work against git-daemon and github Git server implementations. Tests by abieber, naddy, jrick, and myself. Man page additions reviewed by Lucas.

This saves an iteration over the entire h->offsets array when opening a pack index which should not contain large offsets in the first place. ok millert@

The singly-linked tail queue macros were added to OpenBSD 6.9 and are more widely available on other systems. ok stsp

This way, the size of a raw object is the same regardless of whether the object was found in a loose object file or in a pack file.

Avoids an error where tog(1) would exit with "poll: Interrupted system call" while the terminal window was being resized. ok millert

ok millert, naddy

Make use of this in 'got clone' to persist -R option arguments given on the command line in the cloned repository's got.conf(5) file.

Set fetch-all-branches in the got.conf(5) file created by 'got clone -a' in order to make a future 'got fetch' act like 'got fetch -a' by default.

ok millert

ok tracey

POSIX says the limits defined there are available from <limits.h>, which almost all affected source files already included anyway. ok millert stsp

ok tracey

ok stsp