tests/test-rhg-no-generaldelta.t

simplemerge: make minimize() a free function

IMO, `Merge3Text` should be about merging text without knowing about
conflict markers. "Conflict minimization" is about making conflict
markers smaller, so it should be moved out. This patch does that. I'll
refactor it next.

Differential Revision: https://phab.mercurial-scm.org/D11980

  $ NO_FALLBACK="env RHG_ON_UNSUPPORTED=abort"

  $ cat << EOF >> $HGRCPATH
  > [format]
  > sparse-revlog = no
  > EOF

  $ hg init repo --config format.generaldelta=no --config format.usegeneraldelta=no
  $ cd repo
  $ (echo header; seq.py 20) > f
  $ hg commit -q -Am initial
  $ (echo header; seq.py 20; echo footer) > f
  $ hg commit -q -Am x
  $ hg update ".^"
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ (seq.py 20; echo footer) > f
  $ hg commit -q -Am y
  $ hg debugdeltachain f --template '{rev} {prevrev} {deltatype}\n'
  0 -1 base
  1 0 prev
  2 1 prev

rhg works on non-generaldelta revlogs:

  $ $NO_FALLBACK hg cat f -r .
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  footer