reuc: Be smarter when inserting new REUC entries
reuc: Be smarter when inserting new REUC entries

Inserting new REUC entries can quickly become pathological given that
each insert unsorts the REUC vector, and both subsequent lookups *and*
insertions will require sorting it again before being successful.

To avoid this, we're switching to `git_vector_insert_sorted`: this keeps
the REUC vector constantly sorted and lets us use the `on_dup` callback
to skip an extra binary search on each insertion.

skabel/manguse,yongthecoder/libgit2,jeffhostetler/public_libgit2,Corillian/libgit2,magnus98/TEST,magnus98/TEST,yongthecoder/libgit2,saurabhsuniljain/libgit2,yongthecoder/libgit2,Corillian/libgit2,joshtriplett/libgit2,yongthecoder/libgit2,jeffhostetler/public_libgit2,magnus98/TEST,skabel/manguse,leoyanggit/libgit2,KTXSoftware/libgit2,mrksrm/Mingijura,saurabhsuniljain/libgit2,Tousiph/Demo1,KTXSoftware/libgit2,stewid/libgit2,Tousiph/Demo1,joshtriplett/libgit2,Corillian/libgit2,joshtriplett/libgit2,stewid/libgit2,saurabhsuniljain/libgit2,jeffhostetler/public_libgit2,KTXSoftware/libgit2,mrksrm/Mingijura,mrksrm/Mingijura,mrksrm/Mingijura,leoyanggit/libgit2,stewid/libgit2,Tousiph/Demo1,magnus98/TEST,saurabhsuniljain/libgit2,Tousiph/Demo1,jeffhostetler/public_libgit2,jeffhostetler/public_libgit2,skabel/manguse,saurabhsuniljain/libgit2,skabel/manguse,Tousiph/Demo1,skabel/manguse,KTXSoftware/libgit2,yongthecoder/libgit2,KTXSoftware/libgit2,jeffhostetler/public_libgit2,leoyanggit/libgit2,stewid/libgit2,joshtriplett/libgit2,yongthecoder/libgit2,leoyanggit/libgit2,magnus98/TEST,magnus98/TEST,mrksrm/Mingijura,joshtriplett/libgit2,Tousiph/Demo1,mrksrm/Mingijura,leoyanggit/libgit2,KTXSoftware/libgit2,stewid/libgit2,saurabhsuniljain/libgit2,Corillian/libgit2,leoyanggit/libgit2,skabel/manguse,Corillian/libgit2,stewid/libgit2,Corillian/libgit2,joshtriplett/libgit2