sync files from diff.git 35eae7fa6b782ae1d000183ef2efc4383dfec4cd This removes the gcc ternary if extension (includes follow-up diff.git fix for missing '\' in wrapped macro 7a38b3a33f8b124c9c01da154dfdf711d328b01d)

sync files from diff.git 3a15e1807a369c0a7827363eca22c9f1a8598d9c Rather than realloc in fixed-sized blocks, use the 1.5 * allocated scheme when growing the array. This produces fewer allocations and up to 3x speedup on large diffs. ok stsp@

merge new diff implementation from the git.gameoftrees.org diff.git repository This new diff implementation was started by Neels Hofmeyr during the u2k20 hackathon and now replaces diffreg.c code lifted from the OpenBSD base system. The integration of this code into Got was done by me. Got now uses the patience diff algorithm by default. The diff.git repository will remain the primary repository for the diff code, which already compiles and runs on other operating systems such as Linux. Any fixes and improvements for files inherited from the diff.git repository should be written against that repository and synced to got.git afterwards.