Fixes buildsystem: - "[[" is bash-specific. If /bin/sh is dash, which   is the default on many Linux distributions, it will not work. - "$( ... )" gets executed by make before the recipe gets executed.   So "$(shell cat vfconfig.ml)" will always be evaluated, even   if what it evaluates to is not always evaluated.   So in     if [[ -e vfconfig.ml && "$(shell cat vfconfig.ml)" != "$(VFCONFIG_CONTENT)" ]]   the "cat vfconfig.ml" will always unconditionally be executed. - pattern-rules (e.g. "%.cmx: %.ml") do not seem to be enough for   reloading the dependency graph concerning .ml files, so I added   an explicit dependency "vfconfig.cmx: vfconfig.ml". - Autogenerated files need to be cleaned as well.
Fixes buildsystem:
- "[[" is bash-specific. If /bin/sh is dash, which
  is the default on many Linux distributions, it will not work.
- "$( ... )" gets executed by make before the recipe gets executed.
  So "$(shell cat vfconfig.ml)" will always be evaluated, even
  if what it evaluates to is not always evaluated.
  So in
    if [[ -e vfconfig.ml && "$(shell cat vfconfig.ml)" != "$(VFCONFIG_CONTENT)" ]]
  the "cat vfconfig.ml" will always unconditionally be executed.
- pattern-rules (e.g. "%.cmx: %.ml") do not seem to be enough for
  reloading the dependency graph concerning .ml files, so I added
  an explicit dependency "vfconfig.cmx: vfconfig.ml".
- Autogenerated files need to be cleaned as well.

This patch is not tested on Windows.

willempx/verifast,willempx/verifast,willempx/verifast,willempx/verifast,willempx/verifast