Very unlikely (an occurrence of it would mean that got produced an invalid fileindex) and harmless anyway since we would just terminate, but a leak is still a leak. ok stsp@

problem found by naddy@ ok op@

This adds a set of functions to abstract over SHA1Init, SHA1Update, SHA1Final, their respective SHA256 variants and how to compare digests. Replace all the SHA1*() usage with the new APIs. It's a preparatory step for sha256 handling. ok stsp@

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>

ok stsp

Accept flag parameter to optionally specify which pointers to free. This saves callers looping through the list to free pointers. ok + fix stsp@

ok stsp@

Problem found and fix tested by Ted Bullock. ok millert, naddy

suggested by millert ok thomas_adam

Fixes regression introduced by commit 41f061b2f459318f3738f59d7676efccc4beb344 where tracked files inside an ignored directory were reported as missing.