portable: configure: split out dependencies Rather than assume all dependencies are required for all programs, split them out. This will make packaging easier, as well as splitting the code to use subprojects. Note that due to the use of config.h semantics, in most cases the got_compat.h header file is now at the top of the .c file it is included in, so that it can handle the system header inclusion properly.

portable: rework SHA detection Simply the SHA detection by not predicating on libcrypto, but instead checking individual header files.

portable: remove sha1.h; found portably Remove sha1.h as this is found portably across systems.

include sha2.h too where sha1.h is included In preparation for wide sha256 support; stsp@ agrees. Change done mechanically with find . -iname \*.[cy] -exec sam {} + X ,x/<sha1\.h>/i/\n#include <sha2.h>

got-read-gitconfig: send key-value pairs for extensions Most extension allow only for a boolean value so the current behaviour of just sending the extension with a trueish value is fine. However, some extensions that we could eventually support (like "objectformat") have a string value. This is a preparatory step towards that. ok stsp@

use sub-second precision when checking for objects/pack/ modification Convert from st.m_time (second-precision time_t) to st.m_tim (struct timespec). To compensate for the potential case where a filesystem provides resolution in seconds only, always read the directory if no pack files are known to exist. Otherwise, there is a race condition when gotd repo_write creates a new pack and a request arrives for repo_read shortly after. Caught by a regression test for gotd on empty repositories. Test failure pointed out by Mikhail. ok op@

portable: handle sys/tree.h Unfortunately, MacOS doesn't provide sys/tree.h -- so the compat check for this must happen portably.

portable: remove sha1.h include This is searched for portably.

move code for reading Git's config file into new file read_gitconfig_privsep.c The end goal here is to remove the dependency of repository.c on privsep.c during compilation.